Newcastle United defender Florian Lejeune could miss the rest of the season.
The French centre-back picked up a thigh injury against Hull City in a warm-up game ahead of Project Restart.
Lejeune has not played since scoring a dramatic brace in stoppage time at Everton in the 2-2 draw back in January.
The former Eibar defender has appeared just six times in the Premier League this season.
Bruce said: "It's going to be touch and go for Florian Lejeune if he'll play any part [in the season].
"He's picked up a nasty thigh injury against Hull which is a grade two.
"I think he's 17 days in to what we thought might have been around four weeks out."
Lejuene had started the season with a knee injury and had to play in the Under-23 side to prove his fitness.
