Diogo Dalot called Bruno Fernandes' injury a "massive" blow as Manchester United wait to find out the severity of the skipper's setback.
The ever-impressive 31-year-old has started every Premier League game for the Red Devils this season, scoring five goals and providing seven assists along the way.
But United boss Ruben Amorim fears Fernandes will now be ruled out for "a while" due to a soft tissue injury that led to his withdrawal at half-time of Sunday's 2-1 loss at Aston Villa.
"It's massive," Dalot told Sky Sports. "We don't know how bad it is but for him to come off [in] the game, we know how tough he is."
Dalot, who took the captain's armband from his compatriot, then told MUTV: "We obviously were sad that Bruno came off. I think we found a way to keep in the game and try to find ways of playing, creating chances.
"I think we still created enough to score more goals and let's hope that it's not too bad and then we have Bruno for the next games."
While the prognosis is unclear, Amorim has already ruled Fernandes out of United's Boxing Day clash against Newcastle United.
Natural replacement Kobbie Mainoo is also set to miss out with a calf issue sustained in training on Saturday, meaning United could be without seven first-team players in their next match.
Amad Diallo, Bryan Mbeumo and Noussair Mazraoui are at the Africa Cup of Nations while Matthijs de Ligt and Harry Maguire have missed recent games, which has seen Amorim turn to the academy.
Jack Fletcher, son of United favourite Darren, and Shea Lacey came on for their senior debuts at Villa Park and other academy talents are knocking on the door.
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"This is the moment," Dalot said. "I mean, we have so many players missing that this is the opportunity for those who didn't have so many chances to step up now and show that they deserve more minutes.
"I'm very happy that they could make their debuts and hopefully in the next games they are available and they can help us as well."
United head into Christmas seventh in the Premier League, whereas Sunday's victors Villa are third -- just three points behind leaders Arsenal -- having racked up a 10th-straight win in all competitions.
Morgan Rogers was the star man on Sunday as he followed up last weekend's impressive brace at West Ham with another matchwinning pair to help Unai Emery's side over the line.
"I feel like I'm playing the best I've ever played," the in-form England international told VillaTV.
"I'm the most confident but that's also within the team. The team is the most confident it's been since I've been here.
"It's no surprise individual performances rise when we're doing well as a collective.
"We're all confident in each other, the manager's confident in us and we go out there and we feel like we're going to win every game."
