Slaven Bilic has challenged Andy Carroll to fill the void left by West Ham's injured shooting stars.

The Hammers this week lost five-goal frontman Diafra Sakho for at least two months due to a thigh injury, joining fellow attackers Dimitri Payet and Enner Valencia on the sidelines.

Carroll has been used largely off the bench this season as he builds up his fitness following ankle surgery, and memorably headed the winner as a substitute against Chelsea in October.

But Upton Park boss Bilic now needs the former Newcastle and Liverpool target man to perform from the start, beginning at Manchester United on Saturday.

"Andy is trying hard in training, and has played well in the few games that he has played for us," said Bilic.

"So far he has showed his class more as an impact player, to come on in the last 20 mins or half an hour and lift our game.

"But also he has to show it when he plays from the start. We hope he is going to do that now for us."

Bilic said of Sakho's injury: "It's not good. It will be four to eight weeks. Maybe more.

"He has a bit of history with his thigh. It's a muscle injury. Nothing long term, but we will be without him for a few games, definitely."

French playmaker Payet has been sorely missed since he was injured against Everton last month but another of Bilic's summer signings, Manuel Lanzini, has continued to impress.

The Argentinian midfielder, on a season-long loan from United Arab Emirates side Al-Jazira, has scored four goals this term and his performances have reportedly alerted a host of rival clubs.

However, co-chairman David Sullivan insists they have an "unbreakable option" with Lanzini's parent club and Bilic is confident West Ham will sign him permanently.

"Yes I would like to make his move permanent," he said.

"He has proved himself as a key player for us. Also the way he is playing all the games, he has been really good for us.

"I would like him to stay and as the chairman said, he is our player. He's happy here and we are happy with him. I think it's going to be a long relationship between him and West Ham."