LONDON (REUTERS) - Former Manchester United striker Mark Hughes believes his old club are "a little bit vulnerable" as he prepares his Stoke City side for Saturday's Premier League clash at Old Trafford.

New United manager David Moyes has endured a rocky start since replacing Alex Ferguson in the close season and his side have already dropped 13 points in eight matches.

Hughes has also found things difficult since taking over as manager of Stoke but believes it might not be a bad time to be playing the champions.

"There are only a certain amount of games you can lose,"Hughes told a news conference. "They've lost three and maybe they are a little bit vulnerable at the moment.

"Five or six defeats enable you to still be in the title race. Lose any more than six then you make it very difficult, nigh on impossible, for yourself."

United are eight points behind leaders Arsenal but Hughes said the departure of Ferguson, who won 13 league crowns at Old Trafford, would inevitably lead to a dip.

"Some players can deal with change easier than others," said the Stoke boss. "That may be the problem there in regards to their slow start, it can take time to find your comfort zone.

"I am not privy to the information. I am just guessing it may be one of the factors there," added Hughes.

"I think David probably expected the reaction he has had because he has stepped into the shoes of a great footballing man. It will be difficult for any manager of Manchester United." Hughes believes United will still be in the mix for the title despite their slow start.

"They are a little bit adrift at the moment but if you ever question Manchester United, more often than not they will hit back with the answers," he said.

"I would think that they will be there or thereabouts come the end of the season."