Every now and then, there is bound to have an extremely talented young footballer who is billed as the next Maradona, Zidane or Giggs.

However, many of these wonderkids fail to realise their potential either due to excessive pressure or get lost in the world of riches and temptation, or simply they are not good enough for the game as they grow older.

Below is sgParlay.com's Top 10 Wonderkids of the Yesteryear (not in any order) that failed to shine.

If you do not agree with the list or have a better nomination, you may email me at admin@sgparlay.com.

Also find out the Top 10 Wonderkids to Superstars

Javier Portillo, born on 30th March 1982, was tipped to become the greatest player to emerge from Real Madrid's youth academy after Raul and Iker Casillas.

The pacy striker entered Real Madrid C team in 1994 at an age of only 13, and in his 7 seasons at the youth team, he scored 150 goals, breaking a previous record set by the legendary Raul.

In 2001, Portillo was drafted into Real Madrid B team, where he continued his fine form with 15 goals in 23 games. A year later, he was promoted to the senior team consists of Galacticos such as Raul, Figo, Zidane and Roberto Carlos.

In his debut season, Portillo performed superbly as he hit 13 goals in 16 league and cup games. However, in the next season, his form dipped and with the arrival of Ruud van Nistelrooy in 2006, Portillo's chances were limited and he was loaned out to other clubs.

Since then, he has played for Gimnastics and currently Osasuna but the great expectation of him to become a world class Spanish striker never really happened.

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He was supposed to be the new golden generation of Portgual, but Hugo Viana (born 15th January 1983) failed to live up his name after all these years. Viana was a product of Sporting's youth academy, and in 2002, he won the Young European Player of the Year award after an excellent debut season for Sporting.

At age 19 and blessed with superb passing and freekick skills, Viana was signed by Newcastle in 2002 for 9m pounds. Unfortunately, he failed to settle and could not break into the first eleven, and was subsequently loaned back to Sporting.

His stock plunged and Valencia took a risk in him for only 1.5m three years later. Viana continued to struggle and was loaned out once more, to Osasuna, where a pre-season injury limited his chances.

In 2009, a 26-year-old Viana returned to Portugal again, playing for Braga.

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Many young Argentines have been dubbed as the next Maradona, but Andres D'Alessandro (born 15th April 1981), in his early days, has shown flashes of talent that were comparable to the Argentine legend. Left-footed, short and blessed with excellent dribbling and passing skills, 20-year-old D'Alessandro led Argentina to victory in the 2001 Youth World Championship.

A product of River Plate's famous youth academy, D'Alessandro was snapped up by German outfit Wolfsburg in 2003 for a club record of 9m euros. Later that season, he led Argentina to win the Olympics Gold medal.

In Germany, D'Alessandro did not exactly shine in the Bundesliga. The attacking midfielder scored only 8 goals in two seasons with Wolfsburg. Since then, he had two short stints with Portsmouth and Zaragoza. In 2008, he returned to Argentina after failing to make it big in the three major European leagues of Germany, England and Spain. Currently at 28, D'Alessandro may not have another chance to play for a major European club again.

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Darius Vassell, born on 13rd June 1980, was not exactly a wonderkid but he has showed tremendous talent in his early days. After he scored a record 46 goals in a junior league, Aston Villa snapped him up for their youth team. Vassell went on to set a Villa youth record by hitting 39 goals in a single season.

In 1998, the agile and speedy Vassell was promoted to the senior squad. He then played for Aston Villa in the EPL for eight seasons but he has never finished with more than 10 goals in a season apart from 2001/02.

Vassell was transferred to Man City in 2005 but his fortune never improved. With the sudden injection of huge cash into the club in 2009, Vassell was deemed as surplus. He has only 17 goals in 103 games for the Sky Blues. At the end of 2008/09, 29-year-old Vassell made an unlikely move to Turkish outfit Ankaragucu, a sad end for a player that promised so much during his younger days.

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Neil Mellor, born on 4th November 1982, was considered the best striker to emerge from Liverpool's youth academy after Michael Owen. Powerful and strong, Mellor was the top scorer in Liverpool's Under19 and reserve team in 2002, scoring 46 goals. After hitting another 20 goals in the reserve team in 2003, Mellor was handed his debut for the senior squad in a cup game.

Just as Mellor was about to break into the starting lineup, his knees gave way and he had to go for surgery in 2005, robbing his chance of cementing his position in the Liverpool team. Further injuries dampened his progress and he was released by Liverpool in 2006, having played only 12 games and scored 2 goals in his four seasons at the Reds.

Mellor currently ply his trade at Championship club Preston North End. Although still only 26, it is unlikely that he will play for a major club again, not to mention England.

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It is still early to write off a 20-year-old Freddy Adu (born 2nd June 1989), but with his progress so far, he may become one of the most famous wonderkids never to make it at the highest level. Freddy Adu became famous years ago when Italian giant Inter offered hundred of thousands to recruit him. He was only 10 at that time. At 12, Adu joined the US soccer academy and made his debut in the MLS at only 14.

Three seasons in MLS playing for DC United and Salt Lake City, Adu played almost a hundred league games and scored 13 goals. He finally moved to Europe in 2007 but it was Benfica which was not exactly a major club. Monaco loaned him for a season after that but overall, Adu's records in Europe are not really impressive. The small and speedy striker still has room for improvement, and the next five years may be crucial for Adu to determine if he can really realise his potential.

Adu has represented the United States at all levels, including the Under17, Under20, Under23 and the senior squad.

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Luke Chadwick (born 18th November 1980) was supposed to be the next classy winger to play for Manchester United after Ryan Giggs and David Beckham. He was promoted to the senior squad in 1999 after two seasons in the reserve. He was only 18 then.

However, after a handful of appearances as substitute and two goals, Chadwick failed to establish his first team position and was loaned out four times before being released by the Red Devils in 2004.

From then onwards, Chadwick's clubs seems to shrunk in size and status and currently he is playing for MK Dons in English League One. The former England Under21 winger is now 28 and is unlikely to make it big in his playing career again.

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Both players are cousins and worth a mention in this column as they were considered wonderkids after their impressive performances in the FIFA Under17 World Championship in 2001, where Sinama-Pongolle (born 20th October 1984) won the Golden Ball award and Le Tallec (born 3rd October 1984) won the Silver Ball.

Both Le Tallec and Sinama-Pongolle were snapped by Liverpool's former manager Gerard Houllier from Le Havre in 2003, viewing them as potentially great players of the future. Both players were only 18.

Three and five years later, Sinama-Pongolle and Le Tallec left the club respectively, without any glaring achievement.

Le Tallec failed to score a single goal for Liverpool, and was loaned out to four different clubs before a permanent move to Le Mans. Sinama-Pongolle had two fine seasons with Recreativo after leaving Liverpool, but was forced to play as a right winger for his new club Atletico Madrid.

At 24, they may still have dreams, but once regarded as the future regulars for the French national team, both Le Tallec and Sinama-Pongolle only share one cap between them so far.

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Emerging from Borussia Monchengladbach at the age of only 15, Sebastian Deisler (born 5th Jan 1980) was once described as the future of German football and potentially the biggest star for Germany after 2000.

At age 22 in 2002, German giant Bayern Munich paid millions in contract terms and signing-on fee for his services. The midfielder-cum-right winger never really took control of Bayern's midfield as he was shaken by a series of knee injuries.

In the five seasons with Bayern, Deisler only played 62 games and scored 8 goals. He has also only played 36 games for Germany, who was hoping to rely on him for World Cup glories.

After many injuries and loss of confidence, Deisler was hit by depression and in 2007, he sadly retired from football at an age of only 27.

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After leading Manchester United youth team to the FA Youth Cup triumph in 1995, John Curtis (born 3rd September 1978) was dubbed as the next big thing and future England right back and captain. He was also expected to replace Gary Neville when the latter eventually retires.

However, three years down the road, Curtis was unable to hold down a regular place in the Manchester United team after his promotion to the senior squad in 1997. Playing only 13 games in three seasons, Curtis was shipped to Blackburn in 2000. Dogged by injuries and loss of form and confidence, Curtis never realised his potential and changed clubs almost every year after Blackburn released him. He is currently playing for Northampton in English League Two, and at 30, it is unlikely that he will ever play for a big club again.

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It is worthed mentioning an English player called Sonny Pike whose tremendous skills were comparable to Diego Maradona and George Best. At only 7, Ajax snapped him up for their youth academy.

However, pressure got into him and together with his parents' failed marriage, Pike suffered a mental breakdown in 2000 and retired from professional football in 2003, at an age of only 20. He was the perfect example to warn other upcoming stars to cope against pressure and expectation.

Liverpool's youth academy is famed for producing young British players with huge potential, such as Robbie Fowler, Michael Owen, Steven Gerrard, Jamie Carragher and Steve McManaman.

However, there are also many promising players that either failed to realise their potential or become lost in the later stage of their careers. The most famous includes Neil Mellor (as mentioned earlier), Stephen Wright, Stephen Warnock, John Welsh and Richie Partridge. Many of these former promising youngsters are now plying their trades at the lower divisions of the English League.

Former Arsenal's left winger Jose Antonio Reyes is also an ex-wonderkid that failed to impress, although he is not exactly considered a failure. He burst into the Sevilla senior squad at an age of only 16. Arsenal bought him in 2004 for 17m pounds, but despite a strong start, he became unsettled in London.

Reyes was loaned to Real Madrid in 2006, but somehow the Spanish giant did not make the loan move permanent at the end of that season, and Reyes joined Atletico Madrid instead. Again, he could not last long and was loaned once again to Portuguese club Benfica. At 26, Reyes may still have enough time to make it to top once more..

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