Sir Alex Ferguson warned Manchester United's title rivals that his team would improve in the later stages of the season after opening up a three-point lead at the top of the league with a 2-1 defeat of Stoke City last night.

Nani's winning goal puts United in an increasingly commanding position, with a game in hand over second-placed Manchester City, leaving Ferguson's side on course to overtake Liverpool with a record 19th league title. The victory extends their unbeaten run of league matches to 25 and moves them nine points clear of the champions, Chelsea, courtesy of a 15-point swing since September.

"Once you get to the new year it gives you a good guide to where you are going to be at the end of the season," Ferguson said. "Our history tells us that we play better in the second half and that big games are not an issue for us because we relish them."

Javier Hernández had opened the scoring before Dean Whitehead equalised for Stoke early in the second half. United were missing several key players, including Wayne Rooney and Rio Ferdinand, and Ferguson believes some of the criticism about his team's recent performances has been unfair.

"We're an easy target but we're going to dismiss it and concentrate on our ambition – and that's to win the league."