The two strikers missed Saturday's 4-0 FA Cup fourth round defeat to Manchester City after picking up injuries in the 0-0 draw at West Bromwich Albion last weekend.
Gestede pulled his hamstring in last weekend’s 0-0 draw at West Bromwich Albion just minutes after coming off the bench to replace Kozak, who himself picked up an ankle knock during the game.
Both players subsequently missed Saturday’s 4-0 FA Cup fourth round defeat to Manchester City but Garde is hoping that at least one of them will be fit for the trip to east London.
Asked about the pair’s status, the Frenchman said: “They are both injured. Rudy injured his hamstring against West Brom and Libor received a bad kick on his ankle in this game.
“Hopefully one of the two will be fit for the Tuesday game.”
Meanwhile, with Villa struggling for goals even when either Gestede or Kozak has been in the line-up, Garde is also hoping to sign a new striker before the winter transfer window closes.
The ex-Lyon manager is yet to make his first acquisition as Villa boss as Monday’s 11pm deadline approaches and he is more than aware of his need for a proven finisher after seeing his side score just 11 goals in his 15 games in charge since replacing Tim Sherwood at the helm in November.
The club’s position at the foot of the Premier League has made it tough to attract new recruits who can improve the squad so far this winter, but the former Arsenal midfielder is still expecting at least one new arrival.
Asked whether a deal for a goalscorer is in the works, Garde told avfc.co.uk: “I would like - and am still expecting. I still have hope that I will sign one player, yes.”