LONDON (AP) -- Chelsea captured its second straight Premier League title Saturday with a 3-0 victory over second-place Manchester United, which lost star striker Wayne Rooney in the second half with an injury. William Gallas scored on a header in the fifth minute, with the other goals by Joe Cole in the 61st minute and Ricardo Carvalho in the 73rd. Chelsea, which needed only a point to clinch the title, won the championship with two games left. Rooney was carried off the field with 10 minutes to go with what appeared to be a serious foot injury. He went down after being challenged by Paulo Ferreira. With the World Cup only six weeks away, the timing is bad for the English team. "He's got a heavy knock," United manager Alex Ferguson said. "We will see when we get back to Manchester. We don't want to make any opinions at this stage, but he's in the right hands with the doctors we we'll have to wait and see." Cristiano Ronaldo lost the ball just inside his own half when he was tackled by Frank Lampard and United was forced to concede a corner kick. Lampard's cross was headed on by Didier Drogba and Gallas was unmarked in front of goal. Rooney was positioned to tie it in the 25th minute when he drifted past two Chelsea tacklers. He had only goalkeeper Petr Cech to beat, but he rolled the ball well wide of the post. A minute before halftime, he forced Cech to make a blocking save with a low, right-footed shot, and then John O'Shea headed too high after Chelsea failed to clear a corner. On the second goal, Cole turned past Rio Ferdinand and Nemanja Vidic and then left Mikael Silvestre behind before racing clear to shoot between goalkeeper Edwin van Sar and the near post. Twelve minutes later, it was 3-0. Carvalho won possession to start the move and the ball went through four passes until the defender collected a diagonal pass from Cole. He was unmarked on the left side of the United area and drove home a shot from 15 yards.