LONDON - Teenager Federico Macheda's brilliant winner last weekend merely papered over the cracks in a Manchester United team floundering in their defence of the Premier League title. When they visit Sunderland on Saturday, United may find themselves once again looking to claim back their one-point lead from Liverpool whose home kickoff against Blackburn Rovers is two-and-a-quarter hours earlier. Last weekend, Liverpool went top on the Saturday with a last-gasp 1-0 victory at Fulham and United managed to claw their way back from 2-1 down at home to Aston Villa before 17-year-old Italian Macheda's late winner. The United defence, still without the injured Rio Ferdinand, had a tough time again on Tuesday when Porto secured a deserved 2-2 draw in the Champions League at Old Trafford. The champions lost central defender Jonny Evans to a groin injury during that match, making him doubtful this weekend and reducing their options further. "They're conceding goals and we have to take advantage of that," Sunderland manager Ricky Sbragia told Sky Sports News. With Ferdinand and Nemanja Vidic as their first-choice centre back partnership United went 14 league matches without conceding a goal between mid-November and mid-February and built a seemingly unassailable lead over their rivals. "We had a record to defend and when we lost the first goal against Blackburn (in a 2-1 win) things began to turn," Ferguson was quoted as saying. However, with regular potential match-winners at his disposal in Cristiano Ronaldo, Wayne Rooney and Carlos Tevez, Sunderland, one place above the relegation zone, ought to be easy meat for United. RAFA'S SMILE The frown on Ferguson's forehead contrasts with the smile on Rafa Benitez's face over the form of his Liverpool side, who have gone on the rampage since appearing to blow their title hopes with a shock defeat at Middlesbrough on March 28. Benitez, speaking about his now cooler relationship with Ferguson, was quoted in British newspapers on Wednesday as saying: "I just think he's a little bit scared. I think he is now worried about us and the challenge Liverpool can make." Guus Hiddink's third-placed Chelsea are also still in with a shout, four points behind United and three shy of Liverpool. Chelsea are at home to Bolton Wanderers. Fourth-placed Arsenal visit Wigan Athletic looking for a win that will keep them at least six points ahead of Aston Villa in the race for England's fourth Champions League berth next season. Villa are at home to form side Everton, only one point behind them in sixth, on Sunday.