His hopes of reaching a first Champions League final sincehis Barcelona side beat Manchester United 3-1 in 2011 were dented after Saul Niguez's brilliant solo goal gave Atletico a 1-0 first-leg victory.
With Guardiola leaving for Manchester City at the season's end, this is his last chance to conquer Europe with Bayern, who won the first of their five European Cups by defeating Atletico in the 1974 final.
"It's not over yet, we still have a chance," Guardiola told reporters. "If we lose it, you can kill me, but we still have a chance."
Atletico coach Diego Simeone also believes the tie is open.
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"Playing in Munich means they'll have their fans supporting them, but we have the opportunity to score an away goal."
"We need to be on fire on Tuesday," said Thomas Mueller, who shone as Bayern were held 1-1 by Borussia Moenchengladbach on Saturday and were consequently made to wait for their fourth consecutive Bundesliga title.
Mueller's return was one of eight changes from the Atletico match made by Bayern, who were boosted by the return of Jerome Boateng, who had not featured since January.
Arjen Robben, sidelined for two months with a hamstring injury, says that he is "fighting" to return this season but will miss out, while Guardiola confirmed he does not know whether Franck Ribery will recover from a back complaint.
"We'll do everything we can to have Franck back," said Guardiola, who is also without defender Holger Badstuber.
While Bayern were unconvincing on Saturday, Diego Simeone's Atletico are finishing strongly in Spain, having won their last six league games and keeping four consecutive clean sheets.
They are level on points with La Liga leaders Barcelona after defeating Rayo Vallecano 1-0 on Saturday.
"It'll be a close game like today's match," said Simeone after the Rayo game. "We'll see who makes the most of their chances."
Influential central defender Diego Godin returns from a hamstring injury, Yannick Ferreira Carrasco is also available and Tiago Mendes travels despite not yet being passed fit to play.
(Writing by Ed Dove, editing by Ian Chadband)
