David Moyes faces an anxious wait to see how bad the damage is to Victor Anichebe's damaged hamstring.
The Sunderland striker limped off in first-half injury time in the 4-1 mauling at Burnley and faces a potentially lengthy spell on the sidelines.
Anichebe was hurt when giving chase to George Boyd as the Clarets counter-attacked after clearing a Black Cats free-kick.
“Victor has pulled his hamstring," said Moyes.
"I’ve not checked with the medical team as yet how bad or good it is at the moment, so we’ll just have to see how he is."
Anichebe limped out of Turf Moor and, given the nature of such problems, his recovery time could be around four weeks-plus.
The powerful striker's injury put the seal on a hideous afternoon for the relegation battlers.
They lost Jason Denayer before kick-off with the Belgian feeling his hamstring, though Moyes hopes he could feaature against Liverpool on Monday at the Stadium of Light.
Sunderland lost Lamine Kone on 24 minutes, also to a hamstring problem after he slid into the advertising hoardings.
“I thought he was going to be OK but I couldn’t really see it from the dugout, " said Moyes. "It looked not so bad to me at the time but I’ve got no idea [how bad it is].”
Whatever could go wrong for the away side did, with Andre Gray taking advantage of some woeful defending to plunder a hat-trick, his goals coming on 31, 51 and 53 minutes.
To continue the theme of calamitous defending, Seb Larsson's poor tackle conceded the penalty which allowed Ashley6 Barnes to make it 4-0.
Jermain Defoe pulled one back with a cool finish but it was a painful day in more ways than one as Sunderland missed the opportunity to come out of the drop zone.
"It shouldn’t have gone wrong like this," said Moyes. "We’d been doing OK [defensively in previous matches].
"But I don’t think we gave ourselves a chance defensively - we didn’t cope with anything well at all."