LONDON (AFP) - Manchester United striker Zlatan Ibrahimovic has performed so well that he has made himself virtually undroppable this season according to manager Jose Mourinho.

The 35-year-old former Sweden international has found the net 14 times in all competitions for United this season after he joined from French champions Paris Saint-Germain on a free transfer.

He has also played in more matches than any of United's other strikers this season, featuring in 24 of their 26 games so far, and will start up front in the Premier League clash with in-form West Bromwich Albion on Saturday.

"Is it almost impossible to leave him out? Yes, it is," said Mourinho at the eve of match press conference on Friday.

"As a striker he is one of the impossible positions where you cannot hide. He is phenomenal and plays again tomorrow (Saturday) and then one week to rest."

Mourinho, who enjoyed a good relationship with Ibrahimovic at Inter Milan when he was in charge there, said he would need to rest him but he was such an integral part of the side it was hard to omit him.

"I must give him a rest. I must leave him out a game," said Mourinho. "But as our target striker we can see he is the only one. And the way we normally play we need him."