Manchester United boss Sir Alex Ferguson has no concerns over Wayne Rooney's scoring duck so far this season.

Rooney is yet to find the target for Ferguson's team this term, something both Carlos Tevez and Cristiano Ronaldo have managed, and it would be no surprise if the 22-year-old found it was his turn for a rest when United tackle Bolton searching for their first home Premier League win on Saturday.

Yet Ferguson insists he is not concerned for the young Merseysider.

"Players are still trying to find their fitness," argued Ferguson. "Wayne is not getting a lot of chances at the moment but Liverpool and Chelsea are hardly the easiest places to go.

"It is difficult to judge the goalscoring performance of any player when you have those two games right at the start of a season."

Ferguson was able to confirm Rooney will be left out at some stage during the campaign. But it will have nothing to do with the former Everton striker's form.

Rooney may have developed a welcome reputation for wanting to play every minute of every game. However, in modern-day football it is just not possible.

"For us to achieve what we want to achieve we need four strikers," said Ferguson.

"I have been saying for over a year now we have been operating with two strikers, which is ridiculous for a club of our size.

"It is not always a matter of who is playing the best or who I prefer. It is a matter of keeping the freshness in the team.

"There is an art to keeping strikers fresh.

"You go back to the four strikers I had in 1999, Dwight Yorke and Andy Cole were always just in front but it was Ole Gunnar Solskjaer and Teddy Sheringham who scored at the most important time."