He was an integral part of Greece's Euro 2004 winning squad, during which he became the only player to score a silver goal in an international football match.

Dellas started playing football professionally in 1993 at Aris for two years, where he helped the Thessaloniki side qualify for the 1994–95 UEFA Cup.

Dellas had a fairly good presence for two years in the team, but a fall-out in 2001 with then-club president Makis Psomiadis and head coach Fernando Santos led to his release.

However, Dellas was dropped from Perugia's first team after a disagreement over his contract and he did not make a single appearance in the last six months of the season, playing only eight matches overall.

He earned the peculiar honour of being one of three players alongside Francesco Totti and Vincenzo Montella who were not consistently booed by the fans during training and games during Roma's disastrous 2004–05 season.

He would eventually miss nearly 8 months of football due to back and hernia injuries and thus, expected offers from the big clubs of Europe failed to materialize.

Here Dellas played alongside players like Rivaldo, Pantelis Kafes and the talented Sokratis Papastathopoulos.

[8] Dellas helped the team to qualify for the UEFA Champions League in the season 2008–09, in the same group with his rival club when he was at AEK, Panathinaikos and Inter Milan of José Mourinho.

On 5 June 2010, Dellas agreed to sign with AEK Athens again, this time for one year, possibly intending to end his career at the team he supports.

During the semi-finals, he scored the only silver goal ever in the last minute of first half of extra time against the Czech Republic, allowing Greece to progress to the final.

[15] Following AEK's relegation from the Super League, Dellas remained at the club's wheel in Greece's third division, instead of the second tier in order to clear the team's debts.