Jack Ross admits he may have some tough decisions to make on his 18-man matchday squad for tonight's game against Gillingham - with Kazaiah Sterling fighting for a place on the bench.
The on-loan forward has not been part of the Sunderland squad for the last two games, and has only featured briefly off the bench once since his deadline day move from Tottenham Hotspur.
Ross confirmed that Sterling missed the Accrington Stanley draw through injury and hinted that the player could miss out again tonight, despite returning to training yesterday.
"Kaz was unfit," Ross said. "We thought he would be OK but he had to pull out [of the Stanley game] quite late on.
"He's trained [Monday] but obviously it's been a little bit stop-start for him with a couple of knocks.
"At the moment, we can only select 16 outfield players [in the squad] so with us pretty much at full health, there's always going to be four or five who miss out.
"At one stage we were probably having to push some of the boys [who weren't fully fit] but now we can be a bit more measured in that respect."
With Ross looking set to revert to his favoured 4-2-3-1 formation, with Chris Maguire behind lone striker Will Grigg, Charlie Wyke is likely to be the attacking option on the bench, alongside a wide player in either Lynden Gooch or Lewis Morgan.
Sterling may squeeze onto the bench if Duncan Watmore misses out again.
The Sunderland forward completed 90 minutes for the first time since suffering two ACL injuries against Blackpool last Tuesday.
He performed superbly and after sitting out the 2-2 with Accrington Stanley on Friday night, Ross had hoped he would be available for a crucial game.
That could still be the case, with Jack Ross set to make a late call on his availability.
"We've got a couple of players that we'll have to look at on Tuesday morning," Ross said.
"Duncan falls into the bracket of ones who might be a doubt."