The Germany international feels his side reacted well at half-time as his first goal in 95 appearances helped the Bundesliga leaders to a 2-0 win over Nurnberg
Mario Mandzukic put the Bundesliga leaders in front in the Bavarian derby on Saturday but they had to wait until the second half for Lahm's first goal in 95 appearances to seal the three points.
Lahm believes the playing surface meant his side were forced into a more direct approach in the opening 45 minutes and was thrilled with the way they improved their standard after the break to stretch their unbeaten league run to 45 games.
"We didn't start very well and while this shouldn't be any excuse, the pitch wasn't great when you want to play your way out from the back," Lahm was quoted as saying by the official Bundesliga website.
"That meant we had to play more long balls and then had difficulty with the second ball as more of them went to Nurnberg than to us. We reacted well at half-time and then were better in the second half."
Mario Gotze felt die Roten took control once Mandzukic opened the scoring after 18 minutes and insists the victory - their 18th in 20 league games this season - was fully deserved.
"The game was completely different after we broke the deadlock. We deserved to win," said Gotze.
Bayern now take on Hamburg in the DFB-Pokal on Wednesday.