Then after series of good matches, Levski qualified for UEFA Europa League after eliminating Dundalk F.C., Kalmar FF and AIK Fotboll.

Levski was drawn in Group C, facing Gent, Lille and Sporting CP.

At the end of the season, Levski Sofia finished 2nd and Petrov was released from the club.

[3] His first match in charge of the team was a March 2021 World Cup qualifier against Switzerland, which Bulgaria lost by a score of 1:3.

[4] On 5 June 2022, Petrov resigned after a 2:5 loss against Georgia in a Nations League match.