David Beckham hailed Wayne Rooney as one of the best players in the world after he fired Manchester United into the Champions League quarter-finals.The England striker scored twice, as he did in the first leg, as United beat AC Milan 4-0 to seal a 7-2 aggregate win.Milan midfielder Beckham said: "Wayne is such an exceptional talent."Without a doubt he is one of the best players, if not the best, in the world at the moment with Cristiano Ronaldo and Lionel Messi."Rooney was again in irresistible form as United romped past Milan on an emotional night at Old Trafford.Despite carrying a 3-2 lead into the tie from the first leg at the San Siro, United were grateful for an early Rooney header to settle their nerves and when the frontman bagged his 30th club goal of the season just after the break, the hosts went on to win comfortably against the Italian giants.United manager Sir Alex Ferguson has challenged the 24-year-old to see if he can surpass the 42 goals Ronaldo bagged in a sensational 2007-08 season."That has to be his goal now doesn't it?" said the Scot. "He continued tonight what he has done all season - he was absolutely sensational."(But) it was a marvellous performance from all my players, especially in the second half when our second goal effectively ended the contest."When we play with that tempo we're very difficult for anybody to play against."Ji-Sung Park, in particular, showed sacrifice, intelligence and discipline and we needed that against [Milan midfielder] Andrea Pirlo."Asked who he would like to face in the last eight of the competition, Ferguson added: "With the kind of team I've got, it doesn't matter who we get."Beckham, despite his disappointment on the night, admitted he will remember the occasion for a long time thanks to the rapturous reception he received from United's supporters."It was a disappointing night because we lost the game, but returning here is always special," he added. "It was an unbelievable reception I got, incredible, and I have to say thank you."If this is my last appearance at Old Trafford, I'll take the memory of the fans away with me - they were incredible."Of course I now want United to go on and win it. They deserve it."