London:Wayne Rooney scored and limped off with a hamstring injury inside the first six minutes of Manchester United's 1-0 win over Wigan on Wednesday that lifted the defending champions into second place in the English Premier League.
The England striker tapped in Cristiano Ronaldo's low cross from three meters (yards) after only 56 seconds, but he was forced off Old Trafford with the injury to his leg about five minutes later.
"With a hamstring you are talking a minimum of three weeks (out)," United manager Alex Ferguson said. "We hope it isn't any longer than that."
Carlos Tevez, who replaced Rooney, and center back Jonny Evans, already playing in place of the injured Rio Ferdinand, completed the game despite taking heavy knocks during the first half.
With a game in hand, United was two points behind Liverpool, which has 46, and United could go to the top of the standings by beating Bolton on Saturday.
Chelsea, which dropped to third place with 42 points, played in the FA Cup and conceded an early goal at League One team Southend in a third-round replay before recovering to win 4-1.
In other replays, Hull beat Newcastle 1-0 and Crystal Palace edged Leicester 1-0.
At Old Trafford, fans were expecting a rush of goals after Rooney scored his ninth goal of the season so quickly, but Wigan threatened like a team coming off the back of a four-match winning streak.
"Rooney gave us a great start," Ferguson said. "We should have put it to bed the amount of chances and penetration we had by halftime, but they made us work."
Rooney's departure provided Tevez with a chance to prove himself to Ferguson as talks drag on to secure a permanent contract at the end of the season. But after beating the offside trap and latching onto John O'Shea's header, the Argentina striker took the ball too far beyond Wigan goalkeeper Chris Kirkland.
Wigan's best chance came when the unmarked Paul Scharner headed into the side netting.
"Wigan are the best side that has played here this season by far," Ferguson said. "It was an outstanding performance from them. They really made us work."
Chelsea's match at Southend was initially called off due to the foggy conditions, but referee Chris Foy reversed his decision an hour before kickoff.
After conceding five goals from set pieces in their last three matches, Chelsea's players spent the aftermath of Sunday's 3-0 loss at Manchester United working on a new zonal marking system. But a third-tier side needed only 16 minutes to breach it, with Southend captain Adam Barrett leaping unchallenged to head Junior Stanislas' corner past Petr Cech.
As chants of "You're getting sacked in the morning" were directed at Chelsea manager Luis Felipe Scolari by the home fans, Cech threw his body at Alex Revell's header from point-blank range and Franck Moussa shot over from the rebound.
But in the last minute of the first half, Michael Ballack produced the equalizer that the dominant visitors deserved.
There was confusion between Southend goalkeeper Steve Mildenhall and Peter Clarke while dealing with Jose Bosingwa's high ball and the half-clearance fell to Ballack to volley into the top corner.
Salomon Kalou spared Chelsea an embarrassing loss by scoring the second goal in the 60th to secure a meeting with Ipswich in the next round. The Ivory Coast winger cut inside Johnny Herd before slotting the ball through the legs of Barrett and into the far corner of Mildenhall's goal.
Joe Cole hobbled off the field with an apparent knee injury before Nicolas Anelka and Frank Lampard scored to complete a comfortable second half.
At St. James' Park, a full-strength Newcastle was eliminated by Daniel Cousin's 81st-minute goal for Hull, which hosts Millwall in the fourth round.