Marko Arnautovic admits the knee injury he picked up during West Ham United's 3-1 win against Everton at Goodison Park on Sunday is concerning him.
The Austria international had been in sparkling form as the Hammers clinched their first three-point haul of the campaign following four consecutive defeats.
Arnautovic set up Andriy Yarmolenko to open the scoring before grabbing West Ham's third goal. However, he had to be substituted shortly after netting with an injury to his left knee.
He said afterwards: "I don't know, we need to check now. It's not my calf, it's my knee. It hurts a lot. We will need to check this week."
However, the former Stoke City star was delighted to emerge victorious on Merseyside, adding: "It was important for us to come back and put in a performance, because we didn't win any of the first four games.
"It wasn't just the forwards. It starts from the goalkeeper and I think everybody did an unbelievable job. The midfield were everywhere and then it's down to us [as forwards] to score the goals to win games."
West Ham, 9/4 to finish in the top half of the Premier League this season, are 6/1 to win their next match on Sunday against Chelsea, while they are available at 7/1 to keep a clean sheet in the encounter.