Roberto Mancini said Zenit did not deserve to take an away goal from their Europa League last-16 defeat at RB Leipzig.
Captain Domenico Criscito curled home a delightful free-kick to give Zenit hope after goals from Bruma and Timo Werner lifted Leipzig to a 2-1 win on Thursday.
Zenit came from a goal down after the first leg against Scottish champions Celtic in the round of 32 to progress, winning 3-0 at home.
But head coach Mancini was critical of the Russian side's performance, with Zenit fortunate Werner wasted a string of chances despite the Germany international converting one opportunity.
"We scored this goal in the end that maybe we did not deserve," Mancini told Sky Sport Italia. "We were too weak in attack, in the second half we did something wrong at the back.
"We are still alive and it's a good result. Zenit is a team that if there is no [suspended midfielder Leandro] Paredes it is hard to play in half of the field.
"We did not have any spare parts in midfield. Mostly everyone did things wrong in the game, we fell after half an hour.
"It also depends on the fact that we are only the fourth game since we resumed [from the winter break].
"For the return leg it's still quite open."
92.6% - Naby Keita was the player with the highest passing accuracy (92.6%) and the most recoveries (12) in the game between RB Leipzig and Zenit St. Petersburg. Boss. March 8, 2018
Despite seeing his side squander a two-goal lead to Criscito's late intervention, Leipzig boss Ralph Hasenhuttl was upbeat.
"We played very well, and we were five minutes away from the perfect result," Hasenhuttl told a post-match news conference. "But the biggest positive is that we have a chance of progressing next week.
"It was important first and foremost that Emil [Forsberg] played 90 minutes. He was everywhere tonight and he made the difference in the second half.
"It's in the balance at 50-50. Zenit only need one goal in the second leg. I think we need at least one goal to progress as well, but we know we have the quality to do that any time."
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