Nemanja Vidic believes Manchester United will have to improve if they want to win the Premier League.
Vidic and his United team-mates managed only their second away win of the season on Saturday at The Hawthorns, narrowly beating West Brom 2-1.
Entering the second half of the season, a period when Sir Alex Ferguson's men are traditionally strong, United sit joint top of the league with fierce rivals Manchester City, albeit with two games in hand.
Yet Serbian defender Vidic points to Chelsea's recent fall from grace as evidence that United must not lose focus during the title run-in.
"We must play better and we need our players back from injury, but we believe we can win the league," said Vidic.
"We have certainly shown this season we can play solid. We haven't lost, but this season is strange. If you told me five weeks ago that Chelsea would be in the position they are now, I wouldn't have believed it.
"Everyone thought they were the strongest team and that they would win the title. But then they didn't win for six games.
"Look how many points we have lost this season. If someone had told me this would happen, I would have said we could not win the league. But here we are top and still unbeaten."
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