Newcastle United midfielder Sean Longstaff must see a specialist to learn about his injury issue.
The Geordie was absent from the 2-0 defeat to Arsenal at home on Sunday.
Whether Longstaff will play in the remaining Premier League games of the season is dependent on the coming days.
Per Chronicle Live, manager Eddie Howe said: "Sean's been an integral part of our midfield, and I think when you take him out, we lose a bit of balance. I think the balance of the team has been so impressive, and Sean does a really important job both in and out of possession for us.
"That's no slight on anybody who came into the team against Arsenal though. I thought it was just a different balance to our team with Alex (Isak) on the left and Callum (Wilson) up front.
"I thought both players played well, but we were up against a very good team, and we still created incredible chances. There were moments where I thought we were going to explode and catch fire, but it never quite happened. But Sean's been a big part of our success."
Howe added: "I certainly hope we will see Sean again this season, but on the specialist's advice, he's going to see a specialist on Tuesday to get it double checked.
"I won't go into the technicalities, but whereas we thought it was quite a standard injury, a bruise, now there may be a chance it's something a bit more serious than that. We're in the dark at the moment."