Jesus Gamez is set to be sidelined until the New Year after being stretchered off on his full league debut.
The Newcastle United defender suffered a suspected broken collarbone in Saturday’s 1-0 Championship defeat to Blackburn Rovers.
Gamez left the field in agony after taking a blow in the second half at St James’s Park.
Magpie manager Rafa Benitez said: “I think that he has broken the clavicle.
“I didn’t see him straight after the game because he went straight to hospital, so now it’s just to fix the problem.”
Gamez, signed from Atletico Madrid in the summer, had only just recovered from a niggling Achilles injury.
Benitez is hopeful that the 31-year-old will make a quick return.
Asked if Gamez was facing a lengthy period on the sidelines, he said: “You never know.
“We will see how things, because sometimes they can fix things quickly.
“Obviously, it will take some time, and I don’t know how long.”
Gamez was making only his third appearance, and first since August, for United.
The former Spain Under-23 international was preferred to Paul Dummett at left-back.
Dummett replaced him in the 55th minute.
Meanwhile, Benitez hopes to have midfielder Jack Colback available for tomorrow night’s EFL Cup quarter-final at Premier League strugglers Hull City.
Colback missed the Blackburn game as a precaution following tests for a vision problem.
Keeper Karl Darlow has challenged his team-mates to put their defeat to Blackburn behind them - by booking a place in the EFL Cup semi-finals.
“It’s good to have the cup game so close,” said Darlow.
“We’ve got three games this week (a league trip to Nottingham Forest follows on Friday), so we know we’ve got to brush this off pretty quickly and get on with things.
“Getting this far in the cup means we’re going to be kept busy, and that’s fantastic for the club.
“We need to concentrate on that now and try to get through to the next round, then it’s Forest on Friday.
“It’s a big week coming up, and we need to put this behind us and get on with it now.”
Ex-Celtic midfielder Charlie Mulgrew scored from a disputed corner to condemn Newcastle to their first league defeat since mid-September.
“You’re going to lose some time, but it’s still very disappointing when it happens,” added Darlow.
“It’s unfortunate that we’ve not played as well as we can, but we’ve definitely had a bit of an off day.
“We’ve had some good victories recently and put a good run together, so it’s disappointing not to keep that going. Hopefully, we can go on another good run now though.
“I don’t think you could criticise a lack of effort or anything like that – it was just one of those days when nothing really clicked.
“We didn’t create too many chances, which was obviously disappointing.
“There haven’t been many teams who have stopped us from scoring this season, but they managed to do that and it was too easy for them really.
“We were disappointing going forward, and defensively we gave them a bit too much at the other end.
“It was one of those games that was going to go either way by the narrowest of margins, and unfortunately it went their way.
“To lose this game, particularly at home, was very disappointing, but now we need to make sure we stay at the top of the league and carry on putting some good performances in. If we do that, we can pick up and really get going again.”