The Bayern coach thinks David Moyes will opt for a conservative approach on Wednesday evening following the 1-1 draw from the first leg at Old Trafford
The Premier League champions held the Champions League holders to a 1-1 draw at Old Trafford last week and the Spaniard believes David Moyes will use similar tactics in the return leg.
"I think they will sit very deep. They play very defensively and always look to counter – it is something they do very, very well," Guardiola said.
"It's never easy against English teams. United are a very big team. Before the first game, everybody was talking about Bayern, but now people know that Manchester can win in Munich.
"But we're playing at home. That's an important factor. If we win, we are through. If not, we are out. It will come down to small details. Our players know, after the experience in Manchester, how United play. My players know their strength and weaknesses."
Bayern will be without key players such as Bastian Schweinsteiger, Javi Martinez and Thiago Alcantara due to suspension and injury and Guardiola admitted that he has limited options to choose from.
"We only have 14 first-team players so I have not got too many options," he said.
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