Guardiola: Barcelona will not rush Messi return
The Argentina forward's presence for the Group D clash could be crucial after the Russians held the Spanish champions in Kazan in last season's group stage and then became one of only three teams to beat the Catalans in all competitions at their Nou Camp stadium in the return fixture.
"The first thing is to look at Leo's ankle," Guardiola said at a news conference.
"He'll train, we'll talk to him and to the doctors. We'll know the situation and we'll decide," he added. "It's a vitally important match but his health is the priority."
World Player of the Year Messi was injured by a late challenge from Atletico Madrid defender Tomas Ujfalusi on September 19 and missed Barca's La Liga victories at home to Sporting Gijon and away at Athletic Bilbao.
He was top scorer in last season's Champions League and netted twice in Barca's 5-1 demolition of Panathinaikos in their opening group fixture earlier this month.
"It's going to be terribly tough (against Kazan)," Guardiola predicted.
"The fact that they took five points out of six off us (last season) shows they are good.
"They dominate the defensive areas in a way I have seldom seen in other teams."
Central defender Gerard Pique said: "This is a test for us to see how we function away from home in Europe."
He said the players were relieved not to have to play in the sub-zero temperatures that marked their trip to Russia in November 2009.
"I don't know if the cold influenced last year's result but for us it's better that it's a bit warmer now," the Spain international said.
Barca swapped their winter outfits for waterproofs on Tuesday as their training session at Kazan's stadium was soaked by a heavy rainstorm.