Due to a Cisse injury, he started the premiere of the 2010–11 season against Xanthi, where he scored the only goal for Panathinaikos in a match that ended 1–1.
Unable to get regular football in five years at Panathinaikos, Petropoulos was released and immediately signed by stricken giants AEK Athens, bottom of Greece Super League with three wins in 15 top-flight matches.
However, since his debut in the 3–1 loss at Asteras Tripolis in early January, he has scored in each of AEK's next three games, with the resulting seven points lifting his side – never relegated – to 12th in the 16-team competition.
"[8] On 20 June 2013 Petropoulos, after the relegation of his former team AEK, signed a €130,000 one-year contract with the newly promoted in Greece Super League, Apollon Smyrnis.
[10] In the summer of 2014 due to Apollon Smyrni's relegation to second division Petropoulos signed for OFI Crete, joined the club for second time in his career.
The Greek winger passed the medical examinations, signing a two years' contract with the club for an undisclosed fee.
After a rather catastrophic season, the Greek striker is going to use his option clause and ask for the termination of his contract with the club as did not manage to be among the first priorities of Andrea Camplone, playing only in five games.
[19] On 9 July 2017, newly promoted to Superleague club Lamia and Aris are monitoring the case of experienced striker, who is expected to leave his current team soon.
On 20 September 2017, he signed a contract with Football League club Doxa Drama for an undisclosed fee.