Newcastle boss Rafael Benitez revealed Dwight Gayle is set for a further spell out after the striker had to be taken off midway through the first half of the 2-0 victory over Aston Villa.
The Magpies' leading scorer had missed six games with a hamstring injury before making his return as a substitute in Tuesday night's 2-2 draw at Norwich.
He was back in the starting line-up to face Villa six days later but a recurrence of the problem means Benitez cannot be certain when the marksman will be back in action.
"Dwight was doing well in training," he said. "He had a baby last week and some days he was not sleeping. Maybe putting everything together, he wasn't that comfortable from the start.
"We had to make the substitution. It's the same problem. He'll miss some games but hopefully it's not too bad."
Newcastle edged ahead in the 42nd minute when Yoan Gouffran pounced in a crowded penalty area to earn the lead before a Henri Lansbury own-goal just before the hour sealed the points and moved the Magpies back to the top of the Championship.
"We said before that every game in the Championship is difficult, we were up against a good team with good players and we have to give credit to them," added Benitez.
"Our second goal was important because we could settle and be more dangerous. They have very good players, they can pass, they can run and beat players one v one. At the moment they maybe don't have the confidence.
"They were asking me about the games we have coming up, but we have to concentrate on every single game.
"Now we have to be strong enough to get three points in every single game. I have confidence that we can still do it. We have to use the squad and we will enjoy this."
There was also an injury blow for Villa boss Steve Bruce, with striker Scott Hogan being stretchered off in the closing stages after going over on his ankle in the penalty area.
Bruce is still waiting for a first win in 2017, dating back to Boxing Day, and that run of form has seen Villa drop to within six points of the relegation zone.
Bruce said: "All in all a very disappointing night for everyone.
"The injury to Scott Hogan doesn't look good. He has gone up for the header and he has turned his ankle over. We will not know the extent of it until (Tuesday).
"It's a nasty one, we will get him back to Birmingham and have him scanned. Fingers crossed.
"We have had a tough eight weeks, I have not known an eight weeks like it. We have to stay with it and hope we can break.
"I can't remember us getting the goals like Newcastle did. Newcastle needed that because up to that, before half-time, I felt we were the better side."
He added: "The situation we are in, of course, we have to accept it, but I am confident we won't (go down). We have to deal with the situation we are in. I don't think I have been on a run like this, eight games or whatever it is. We have to hope things will change for us.
"This club has been in a rut for a couple of years. I can only say the last four or five games, that was exactly the same out there. We have done okay and haven't got a break. When you are up against it we have not had the breaks."