He used the opportunity to impress and scored a hat-trick for the 5–0 win over Litex Lovech in the quarter final of the Bulgarian Cup.

[15] On 12 March, on day when Botev Plovdiv celebrated 106 years from its foundation, Petkov scored in a 4–2 away win over FC Vereya.

[20] On 29 April he scored a goal for the 2–1 home win over CSKA Sofia and won the award for man of the match.

[27] On 4 January 2019, Petkov was transferred to Portuguese Primeira Liga side Feirense for an undisclosed fee, signing a contract until the summer of 2022.

[30] Feirense announced on 1 September 2019, that Petkov had been loaned out to Czech club MFK Karviná until the end of the 2019–20 season.

[32] On 10 September 2022, recently-relegated to Liga Portugal 2 side Moreirense announced the free signing of Petkov on a one-year deal, after his contract with Feirense had expired.

[33] After achieving promotion with the Moreira de Cónegos club, Petkov's contract expired and he became a free agent.

[34] On 28 August 2023, Petkov signed a one-year contract with Liga Portugal 2 club Académico de Viseu.