Kostas Tsimikas will wear the number 21 shirt at Liverpool.
Greek left-back Tsimikas completed a £11.75million move to Liverpool on Monday as much needed cover for Andy Robertson.
Tsimikas wore the number 21 at Olympiakos and at Willem II, when he was on loan from the Greek outfit in 2017.
He said: “I like it as a number. I took it in Holland when I played there, then the next year in Olympiakos and I wore it for two years and now here.”
Tsimikas is Liverpool’s first bit of summer transfer business.
Jurgen Klopp said: “We have watched Kostas for a long time. He is a very good footballer with an attitude to win and to compete, and I really like his mentality.
“It fits perfectly with the mood and the desire we have in our dressing room already.”
On completing his dream move, Tsimikas added: “I’m very happy, I’m very proud to be here. For me, [it’s] the biggest club in the world. It’s an honour to be here and I will give my best.
“The league here, I like a lot. I watch it on the TV and it was always one dream I had from when I was a kid to come to play in this league and to come through.
“With a lot of work and focus on what I do and what the coach wants, and every day working hard in training, I can be on the highest level.
“[I want] to achieve [our] goals. To win the league again and also to win the Champions League.”
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