Aberdeen will be without Jonny Hayes for Saturday's league match against St Mirren and also the game at Celtic Park the following Sunday.
Hayes was withdrawn during last weekend's 3-0 win at Hamilton with a hamstring injury.
Manager Derek McInnes said: "We're disappointed, naturally, but it's someone else's opportunity.
"After the Celtic game we have a longer break until the next game so he should be back for that one."
That match is against Motherwell at Pittodrie on 13 March.
Winger Hayes is an early contender for the Dons' player of the year accolade and his spell on the sidelines is a big blow to McInnes's hopes of pushing Celtic at the top of the table.
"He's an explosive player and his pace differentiates him from a lot of other players in the league," said McInnes.
"He's been a key player for us and while we don't have a like-for-like replacement for the next couple of games, we have other players who can give us options.
"There is a tear in his hamstring and the probability of that becoming worse is real so we've got to look after him.
Aberdeen are currently three points behind Premiership leaders Celtic, who have a game in hand. The Dons are unbeaten in 12 league matches, winning 10 of those.
Recent signing Kenny McLean will feature against former side St Mirren as the Dons seek to secure another victory.
"We've got to keep demanding more," added McInnes. "It is a 13-game season now, that's what it comes down to. Regardless of what's happened previously, what's important is from now until the end of season. We've got to try and win as many of those games as possible.
"At Aberdeen we should be going the full way in any season. We shouldn't be counting down the days until the end of the season with not a lot to play for. We feel we've got lots to play for here and the players are aware that their responsibility is to keep going, not just feel good about where we are.
"My bench in the last couple of games has been really strong so there is plenty of competition to keep everyone on their toes."
Meanwhile, defender Ash Taylor may feature for the under-20 side within the next week after more than a month out with a knee injury.