Mavrias made his debut five days later, coming on as a second-half substitute in a 4–2 home success over Milton Keynes Dons, for the campaign's Football League Cup.

Mavrias returned to Sunderland where he has been training and playing for the Black Cats Under-21s – and is understood to have impressed the club's coaching staff with his attitude and contribution.

[12] On 9 January 2016, almost two years after his last match with the first team, Mavrias entered the game in second half as a substitute in a 3–1 away loss against Arsenal for FA Cup.

[14] Mavrias - who has 18 months remaining on his Sunderland contract - now has a chance to play regular first-team football after joining Düsseldorf until the end of the campaign, with a view to a permanent switch next summer.

[3] On 6 September 2016, after three seasons spent playing for Sunderland, only 7 official caps overall collected as a Black Cats man, plus 2 experiences as a loanee (at Fortuna Düsseldorf and Panathinaikos), he joined 2.

Unfortunately, KSC harboured hopes of promotion back to the Bundesliga this summer, after finishing seventh last term had erupted during the year as the club relegated to Germany's third tier.

[25] On 19 March 2019, Greece head coach Angelos Anastasiadis announced the call up of Mavrias for the match against Liechtenstein and Bosnia and Herzegovina for UEFA Euro 2020.