A year later during the season 2012/13 he scored with the team in a tremendous 3-2 away victory against Olympiakos in Karaiskakis stadium.
Until the end of 2013 Mendrinos has 11 international appearances with Olympiakos and Aris in UEFA Champions League and UEFA Europa League.
On 23 August 2011, Olympiakos Volou and Kavala were relegated to Delta Ethniki for their involvement in the scandal.
He changed his mind and signed with Doxa Drama, on loan from Olympiakos, and consequently he lost his place in the Greece, and he regained it years after in 2007 when he returned to Olympiacos from Skoda Xanthi.
His first European goal for Olympiakos came in a Champions League home win (3–1) against Borussia Dortmund.