West Ham boss David Moyes hopes Michail Antonio will be fit for the trip to Sheffield United.
The 30-year-old has missed the last two games, a 2-1 defeat at Liverpool and the last-gasp home win over Fulham, with a hamstring problem.
The Hammers have missed Antonio, who has become a talisman for Moyes' team playing as an out-and-out forward since football returned after the first lockdown.
Antonio, who has scored 11 Premier League goals during that period, has been recovering over the international break and is back in training ahead of Sunday's match at Bramall Lane.
Moyes said: "Michail is back doing quite a bit of training and we've got a couple of days yet to see how he is. The truth is I can't give you a complete answer (as to whether he'll be available) but he's getting much closer that's for sure.
"What he has done for us over the last few months, his form has been so good. He gives us a different outlet, he can run in behind or hold the ball up. He is a physical presence, his all-round play as a centre forward has improved greatly.
"If we can get him back that would be great, he is a really important player to the team and how we play and if we can get him back good, but I don't want to say if we can because we're not quite sure if he's ready yet."
Angelo Ogbonna is also working his way back from injury after he was forced off against Fulham with a knock.
Moyes thinks the Italy defender has a better chance of being available for selection than Antonio, saying: "Angelo Ogbonna had a problem at the start of the week, but we think he's fine now. He and Michail are the main two really."
Moyes is also waiting for news on his international players ahead of Sunday's return to league action. The Premier League are now testing players for Covid-19 upon their return from international duty, and the Hammers delayed training on Friday in order to allow for results.
"The big problem is we're training this afternoon because we're waiting on all the testing to be confirmed from the international players and we've not had all the tests back, which is a bit disappointing," said Moyes.
"The testing is being done by the Premier League on all the international players who return and we've been guaranteed that all our players would get their test results back in time.
"We put training back today just to give us a bit of leeway and thank goodness I did, or we'd be hanging on to see who was training. Hopefully everybody will be fine but we don't have the results back yet."
