The 23-year-old spent half of last season out on loan at the Greek club before Rovers accepted a bid, believed to be around £3m.

Derbyshire, who has signed a four-year deal, scored eight goals in 11 appearances for the Greek cup winners after moving to Olympiakos in January.

much better

He said: "I am very happy with this transfer. I wanted to stay at Olympiakos.

"I hope to improve myself and become much better next season. I want to score more goals with Olympiakos.

"I am looking forward to going to Austria for the pre-season, it's fantastic the feeling for me.

"I will try my best to help Olympiakos with hard work and I hope to succeed."