Bayern travelled to Porto without the injured David Alaba, Medhi Benatia, Javi Martinez, Franck Ribery, Bastian Schweinsteiger and Tom Starke, although Jerome Boateng was flown in on Tuesday.
Porto have no such injury worries, on the other hand.
Bayern will not repeat the mistakes they made last season in the Champions League on Wednesday night, according to Thomas Muller.
Last year, the Bavarians were unbeaten in the Bundesliga and cruised into the final of the DFB-Pokal until they wrapped up the title in record time.
From that moment, they lifted their foot off the accelerator, lost games in the Bundesliga and, crucially, slipped up against Real Madrid in the semi-finals of the Champions League.
They travelled to Portugal on Monday rather than Tuesday, breaking with tradition to ensure they had no distractions as they look to reach a fourth straight semi-final, and Muller insists there will be no letting up this year.
“We’ve just had two games against Dortmund and Leverkusen which have pulled us even tighter together,” he said.
“All that matters now is being united on the field, and we’ve got lots of self-confidence.”
Bayern go into the game as favourites, but that that will not count for much, as history teaches. In 1987, they were beaten 2-1 by Porto in a final everybody expected them to win.
“To be honest, I wasn’t even born when that game was played so I’ve not had any negative experiences with Porto,” said Muller.
“I’ve never played here and I’m looking forward to it. We know Porto are unbeaten so that means it’s going to be a difficult game.”
That is a view shared by Bayern coach Pep Guardiola, who is taking nothing for granted.
“This is the quarter-finals of the Champions League and that means our opponents are of the highest level,” he said at a press conference. “Porto are a top team.”
The Portuguese side have underlined that by reaching this stage without losing a single game.
“We focus on who we are playing, in this case Bayern, and doing our best,” said their coach Julen Lopetegui on uefa.com.
“We are talking about one of the best Bayern teams in the history of the club. We have a great respect for Bayern, but we have the ambition to be protagonists.”
To succeed, Lopetegui must beat a former team-mate of his from their playing days together with Barcelona, and the Spain national team at the 1994 World Cup – Guardiola.
“I have great respect and affection for Guardiola,” Lopetegui said. “I consider him one of the best coaches in football history.”