Nikolay Odushev’s well-crafted winner secured a second straight win for Uzbekistan to go top of Group C, but Petrov was less than happy with the performance.
"It was our worst match, our worst performance," Petrov said.
"We missed a lot of chances and it wasn’t our real game."
Odushev scored twice while Farruh Farhutdinov also netted a double, with Korea responding with three goals in 75 seconds at the end of the first half.
Petrov said only two of his players emerged with any credit from the win.
"I couldn’t say my team played well – only two players played good enough, the goalkeeper, Rustam Umarov, and Farruh Farhutdinov," he said.
"The others played at a low level."
Petrov believes his side were fortunate to claim victory.
"The match could have gone either way," he added. "We were very lucky."
Hurshid Tajibaev - a scorer of three goals in the 10-0 win over Malaysia on day one - was absent for Uzbekistan and Petrov claimed his presence was missed.
"It was not our strongest side and it was very difficult to play without him," Petrov said.
Korea overcame a two-goal deficit to take a half-time lead, but suffered another late blow a day after Lebanon secured a last-gasp draw on the opening day.
Coach Jeong Jin-hyuk was frustrated by a second late setback.
"The Uzbekistan team is very good at futsal, but we regret that we did not score at the right time," said Jeong, who also criticised the officials for failing to award a penalty kick in the second half.
"We don’t understand the referees’ behaviour," he said.
"If they had given us the second penalty kick we could have won."
Korea suffered injuries to captain Song Ho-young and Sin Han-kook, who are both doubtful for the key fixture with Malaysia on Tuesday.
"Our captain Song Ho-young has injured his ankle – it is a big problem," said Jeong.
"And key player Sin Han-kook has a very big problem with his back.