Full-back Jeremie Frimpong has completed his move to Bayer Leverkusen from Celtic for an undisclosed fee.
The 20-year-old Dutchman has signed a four-year deal with the team currently third in the Bundesliga for a fee that could reportedly rise to £11.5m.
He joined Celtic from Manchester City in September 2019, playing 51 games.
On Tuesday, manager Neil Lennon said Celtic had accepted a "really robust offer" and the player had "made it clear he wanted to leave".
Celtic paid £300,000 to take the defender from Manchester City and Lennon describing Leverkusen's bid as a "huge amount of money".
"We did everything we could to try and entice the player to stay," he added.
"The club had made strides to renegotiate with Jeremie and his representatives but it wasn't the case.
"I wouldn't say he was unhappy. Ambitious maybe, or he wanted to try something else to progress his career.
"The club received a really robust offer and we felt it was good business. He made it clear to me and to the board that he wanted to leave."
Leverkusen signed Timothy Fosu-Mensah from Manchester United earlier this month, while experienced Germany right-back Lars Bender, 31, has been at the club since 2009.
Find all the latest football transfers on our dedicated page.
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