Sir Alex Ferguson has warned Manchester United against complacency when his side take on West Brom at Old Trafford on Saturday.
The Red Devils go into the game with a perfect top flight home record after three wins out of three.
But Ferguson insists the sixth-placed Baggies will be no pushovers after the Premier League newcomers beat Arsenal 3-2 at the Emirates Stadium last month.
Ferguson's side currently sit five points behind table-toppers Chelsea and the United boss knows a repeat of Arsenal's home defeat to Roberto Di Matteo's team would be a major blow.
He said: "You have to recognise that performance at the Emirates Stadium.
"To score three goals there tells you something.
"This will be a tough game, make no mistake."
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