Manchester United can upset the odds and beat Barcelona in Saturday\'s Champions League final because of their manager Sir Alex Ferguson claimed former United star David Beckham on Monday. Barcelona are it is claimed by some as one of the greatest teams in the history of the sport but Beckham told the BBC that he believes if anyone can bring them down to earth it is the wily 69-year-old Ferguson, who has just taken United to a record 19th league title. \"He (Ferguson) can\'t get any better than what he is - he has proved year after year, team after team, player after player what an amazing manager he is,\" said Beckham, who made his debut for United in 1992 before leaving for Real Madrid in 2003. \"To change the players around like he does over the years and still be a success is unbelievable. \"Everyone is talking about Barcelona as one of the best club sides in the world - and of course they are. \"But if anyone can beat Barcelona at their peak, then Sir Alex Ferguson knows how to do that. I hope they go and do that.\" Beckham, who is due to return and play at Old Trafford on Tuesday in a testimonial against Juventus for long-serving fullback Gary Neville who has retired, rubbished claims that this United side lacked the class of its predecessors who had won the title. \"They are up there with the best United sides of all time; the proof is in the trophies they have won,\" said the former England captain, who won six league titles under Ferguson. \"People have criticised the team but you can\'t ask for more than that.\" Should United beat Barcelona it would be the third time that Ferguson has done the league and Champions League double during his tenure.