West Ham United boss Slaven Bilic fears the Hammers could be without striker Diafra Sakho for a while after he was injured in Sunday's 1-1 draw with West Bromwich Albion.

The Senegalese forward was withdrawn after 74 minutes when he fired into the side netting.

Sakho immediately signalled to the bench that he needed to be replaced after falling to a heap inside the penalty area and will now see a specialist to determine the extent of the injury.

Speaking to the club's website, head coach Bilic said: "We still have to wait and the specialist will see him to give an opinion [on how long he'll be out for].

"It looks like a muscle injury and the initial news is not the best. It is a big blow.

“You can see injuries in every club and to be fair the number who are missing is not a lot, but the ones missing are key players who play in the same position. It is very hard to replace them.”

Bilic felt the draw at Upton Park was a fair result with the Hammers' first-half display described as one of their best of the season.

Mauro Zarate put West Ham in front when he bent a sumptuous free-kick beyond Boaz Myhill and into the top corner of the visitors' net after 17 minutes.

But the Baggies stole a point when half-time substitute Rickie Lambert fired in off of Winston Reid five minutes after the break.

“You cannot say it wasn't a fair result," said Bilic. "The first half was one of the best of the season so far.

“We played really well and created good chances. Their keeper made a couple of great saves. We were pleased at half-time with the way we played.

“I asked the players to continue like that and keep the momentum high. We started the second half well but then we conceded a goal and it affected us a lot.

“It gives a boost to the team who scores. We had a few more chances but the game was not so fluent from us in the second half.

“Manuel (Lanzini) and Mauro were involved in most of the moves and they dropped a bit in the second half because they used up a lot of energy in the first half.

“When they dropped a little bit we also dropped and we are not happy with one point but we have to admit it was a fair result.”

Bilic reserved special praise for goalscorer Zarate. The Argentine has five for the season and the Croatian insisted it was no surprise to see him net.

“Mauro has got it and it is a natural talent he has got with the way he shoots," explained Bilic. "Whether it is from free-kicks or open play when he scored against Chelsea.

"He practices that every day in training and it wasn't a surprise to see him do that. It was a great goal.”

Next up for West Ham is a visit to Manchester United. The Hammers haven't won at Old Trafford since May 2007.