5. Hugo Viana (£8.5million)
Neal Simpson/EMPICS SportOfficially the best young player in Europe at the time, having won an award to prove it, Hugo Viana caused a big stir when he signed for Newcastle in the summer of 2002. Thought to be the next big thing to come out of the esteemed Sporting Lisbon academy, responsible for Luis Figo and Cristiano Ronaldo among others, Sir Bobby Robson didn't hesitate in paying a then massive £8.5million for the 19-year-old Portuguese midfielder. But though the late, great former Toon boss did so many great things for the club, and indeed throughout his entire career, this wasn't one of them. Viana was a talent, undoubtedly, proving that by representing Portugal 29 times in 11 years between 2001-2012, but he was never suited to the Premier League and struggled to settle from the start. In many ways, he wasn't given a fair crack of the whip and given his age that is rob ably unfair, but unfortunately the price tag came first, so because he didn't hit the ground running, he was forgotten pretty quickly once he was loaned back to Sporting in 2004. He left permanently a year later, signing for Valencia, but it wasn't all bad for Viana on Tyneside: he will forever be known as a member of the Newcastle side that played Champions League football in the 2002-03 season, his finest moment in a black and white shirt arguably coming in that campaign, when he scored in the famous 3-2 victory at Feyenoord to clinch qualification for what was then the second group phase. His career peaked far too early, and he never reached the heights that his potential forecast, and his journeyman status since leaving Newcastle is testament to that. Although he had five years at Valencia, he was loaned out on two separate occasions before signing on at SC Braga in 2010. His reasonably successful spell there came to an end last year, and he is currently plying his trade at Al-Ahli in Dubai as of last year. Given his price-tag, age and potential, it is without question that Viana goes down as a big money failure for Newcastle. Still aged 31, his career isn't yet over, but there is most definitely a sense of what might have been for this once highly-rated wonderkid.