Goals from Ryan Giggs and Park Ji-sung gave Manchester United a clinical 2-0 win at Middlesbrough on Saturday to extend their lead in the Premier League to six points with four games remaining. The champions were unruffled by a Boro side who offered surprisingly little fight considering they are in grave danger of being relegated and it would now take a monumental collapse by Alex Ferguson's side if they are not to claim an 18th title. "We are whittling the games away," said Ferguson, whose side have 80 points from 34 games. "It's a big step forward today, there's only four games left and eventually there will be none and hopefully we'll still be top of the league." Chelsea are behind Liverpool on goal difference after Nicolas Anelka and Didier Drogba were on target in a 3-1 home defeat of west London rivals Fulham although they have just three games left. Arsenal are fourth with 68 points following a 3-0 victory at Portsmouth. United were without the injured Rio Ferdinand and rested Cristiano Ronaldo, Edwin van der Sar and Michael Carrick in advance of Tuesday's Champions League semi-final, second leg at Arsenal where they hold a 1-0 lead. However, despite the changes they were still able to stroll through a potentially tricky fixture at the Riverside. "Once we got in front that sealed the victory," Ferguson said. "Middlesbrough are a young side and once they had to chase the game it opened it up for us really." Boro could have gone in front just before Giggs scored when Jeremie Aliadiere's shot was saved by Ben Foster. Giggs, voted England's Player of the Year by his peers in the Professional Footballers' Association (PFA) last week, showed his class to put United in front. When the ball came to him on the edge of the area the 35-year-old Welshman looked up, picked his spot, and drilled a low shot past Boro's helpless keeper Brad Jones. Jones almost gifted United a second when he cleared the ball straight to Dimitar Berbatov who set up Paul Scholes but the midfielder shot wide. Boro could hardly get a kick at the start of the second half and a fluid passing move ended with Rooney's reverse pass springing Park to shoot past Jones. The rest of the match was a lesson in possession football by United as they conserved energy for Tuesday while Boro, who are still three points adrift of safety, wilted. Defeat left Boro second from bottom with 31 points with only three games remaining. Newcastle are above them on goal difference while Hull, who go to Aston Villa on Monday, have 34. Bottom side West Bromwich Albion appear doomed on 28 points after losing 1-0 at Tottenham Hotspur while Blackburn Rovers still have relegation concerns after a 3-1 defeat at Manchester City. West Ham United won 1-0 at Stoke City to go seventh while Wigan Athletic and Bolton Wanderers drew 0-0.