Right-back Jamie Hamill is a major doubt for Hearts' next two games, including the Edinburgh derby.
Hamill was carried off on a stretcher midway through the second half of Hearts' 2-0 win against Motherwell.
And the 25-year-old left Tynecastle on crutches due to his heavily swollen left ankle.
"Jamie's a champion. Jamie's been fighting the last two weeks with an ankle problem," manager Paulo Sergio told Hearts TV.
"He has just been running one or two days during the week to be able to play.
"I love to have players with that character and I know with his strength and desire he'll return as soon as possible. I hope it's nothing very serious."
Aberdeen at Pittodrie are Hearts' next opponents before a trip to Hibernian's Easter Road on 2 January.
"It was a very good result [against Motherwell] and it has a special value because it was against a very good team," added Sergio.
"It was a tough game. We were tactically perfect, had a great attitude and used the ball very well.
"It's a players' victory. They deserve it more than anybody else and I'm so happy for them."