Brentford forward Bryan Mbeumo will be sidelined for three months following an operation on his ankle.
Mbeumo, who has 10 goal contributions in 15 Premier League games this season, limped off during the Bees' 2-1 Premier League defeat to Brighton and Hove Albion earlier this month.
“[Mbeumo] will not participate in the Africa Cup of Nations,” head coach Thomas Frank confirmed.
“Bryan is a positive guy. It’s tough to take, but he will come back stronger. He has a very good mindset.”
Midfielder Mathias Jensen (adductor) will also miss Aston Villa’s visit to Gtech Community Stadium on Sunday but could return for the Bees’ game against Wolverhampton Wanderers on 27 December.
Frank is hopeful that Josh Dasilva, who hasn’t appeared for Brentford since the 3-0 victory at Fulham in August due to a hamstring injury, could feature against Wolves in the Emirates FA Cup on 5 January.
Defender Nathan Collins has been training with the group following an ankle injury and “could be ready for selection” on Sunday.
With Rico Henry, Aaron Hickey, Kevin Schade and Kristoffer Ajer also on Brentford’s injury list, Frank admitted that the Bees may look for reinforcements during the January transfer window.
“Of course, the long-term ones are irritating,” he said.
“Almost from game one, we’ve struggled a little bit with injuries. But we still have a good group of players who are willing to fight.
“We need to look at it in January, but we never rush into things; we try to be clever and take calm and sensible decisions. We will not take a player if we don’t think it’s for the longer term.
“Maybe this time a loan, but it depends on how things go over the next three or four weeks.”
Aston Villa are two points off Premier League leaders Liverpool in third and have lost just one of their last 15 games in all competitions.
And the Bees boss was full of praise for the job that Unai Emery has done at Villa Park.
“They’re good,” Frank said. “They play well and it was impressive when they beat Arsenal and [Man] City at home – the winners and runners-up from last season.
“They have a clear structure – offensively and defensively. Unai and his coaching staff are very good, there is no doubt about that.
“Unai has done a top job in many clubs. What I like about him is that he always tries to develop; his high line [at Aston Villa] is not something I’ve seen from his sides before. He’s a student of the game and wants to develop things. He’s a top manager.
“That said - injuries or not a lot of injuries – we know we are a threat against any team in this division and hopefully we will be that on Sunday.
“We will definitely do what we can to play our game plan and execute it well. Hopefully we can get three points.”