West Ham United could be without the services of Diafra Sakho for up to two months as he recovers from a muscle injury sustained against West Bromwich Albion last weekend. The striker featured for the majority of the 1-1 draw at Upton Park, but was replaced by Nikica Jelavic with 16 minutes remaining after appearing to suffer a thigh problem. As a result he will definitely miss the upcoming trip to Manchester United.

After scoring 12 goals during his first season in English football following a £3.5m ($5.2m) switch from Metz, Sakho has struggled to stay fit during the early months of the 2015/16 campaign and already missed a month of action courtesy of a thigh muscle that ruptured in training prior to October's trip to Watford. He returned to the fold during a heavy 4-1 defeat to rivals Tottenham Hotspur at White Hart Lane, but now appears set for another significant lay-off as the Hammers await the results of a recent scan.

"Diafra Sakho, we are still waiting for the results of his scan, but it will definitely not be a couple of weeks – 4 to 8, maybe longer," manager Slaven Bilic was quoted as saying by the club's official website prior to the clash with United.

"We are waiting for the opinion of a couple of specialists. He has a bit of history with that thigh. It's not a light one unfortunately. Of course it's a big blow. We are not bad in terms of quantity of injuries, but unfortunately they have happened to key players."

The momentum driven by West Ham's hugely impressive start to the season that saw them rise as high as third following away victories against the likes of Arsenal, Liverpool and Manchester Cit, in addition to a feisty defeat of Chelsea has notably slowed in recent weeks as injuries to key players have taken their toll.

As well as missing Sakho, Bilic is also currently missing key summer signing Dimitri Payet after the influential French international was ruled out for approximately three months in early November as the result of an ankle injury sustained following a strong tackle from Everton midfielder James McCarthy.

Enner Valencia also suffered an ankle issue during that match and has been sidelined ever since. And while he will not be available for selection this weekend, Bilic hopes to have the 26-year-old back at some stage during the next fortnight as he prepares to start Andy Carroll at Old Trafford.

"Enner is having a good recovery so hopefully we will have him in a couple of weeks time," he added. "It's a good chance for the guys to step in. Andy has lifted our game when he's come in for the last 20 or 30 minutes and now he needs to show that from the start."