Newcastle defender Sven Botman will be sidelined for about eight weeks with a knee issue while the Magpies will also be without Anthony Gordon for the League Cup final on March 16 after opting not to appeal against the winger's red card.
Netherlands international Botman, who only recently returned from a 10-month layoff with an anterior cruciate ligament injury, requires a minor operation.
"With Sven, we've been trying to get him back to full fitness and he was actually very close for the Brighton game (last week in the FA Cup)," Newcastle manager Eddie Howe said Friday.
"Just the day before, one of the last actions in training, he felt the same problem in his knee."
The loss of Botman comes after fellow defender Lewis Hall was ruled out for the rest of the season with a foot issue.
Newcastle travel to West Ham in the Premier League on Monday before facing Liverpool in the League Cup final the following weekend.
The Magpies will be without the suspended Gordon at Wembley after the club decided not to appeal against his red card in last week's defeat by Brighton.
Gordon was dismissed in the 83rd minute after catching Jan Paul van Hecke in the face while challenging for the ball.
"We discussed it as a club with the respective people we needed to discuss it with: lawyers, etcetera," said Howe. "We just felt there probably wasn't sufficient grounds to do that.
"You have to look at it in isolation and review the incident – there was no intention from Anthony."