A Burnley fan was stabbed, and four others were left injured outside Olympiakos' Georgios Karaiskakis Stadium ahead of their Europa League clash, the club has confirmed. 

More than 900 Clarets supporters travelled to Piraeus in Greece for their first leg 3-1 defeat on Thursday night, with the club offering transport to and from the ground to avoid such incidents. 

However, according to a statement via the north west outfit's official website, despite the majority of the travelling fans being "impeccably behaved", five were left injured ahead of kick-off. 

"The vast majority were once again impeccably behaved with the coaching operation to transport supporters to the ground put in place by the club again a great success, as it was in the previous round in Istanbul," the statement read.

"However, five of our supporters were unfortunately injured - including a person who received a stab wound to the leg - and received medical attention at the stadium.

"Those injured all travelled independently to the stadium, outside the organised travel operation.

"Burnley Football Club is working closely with Olympiakos and the local Greek police to investigate these incidents."

The statement went on to add that Greek police arrested 22 ​Burnley fans for drunk and disorderly behaviour; however, were released on Thursday night without charge.

The Clarets now face a tough test to secure passage into the group stages of the competition, with ​a two-goal deficit standing in the way after a first half Chris Wood penalty was not enough to stop Olympiakos taking the advantage. 

The second leg of the tie will be played at Turf Moor on August 30 - the same day both the Europa League and Champions League group draws are made in Monaco.