Borussia Dortmund have exercised their option to sign Nuri Sahin on a permanent deal from Real Madrid, the club announced on Friday.
"We met with Real Madrid officials when the two clubs played in the Champions League quarterfinals, and we have informed them that we intend to make use of the option to buy," Dortmund CEO Joachim Watzke told local paper Ruhr Nachrichten.
"Both clubs have agreed not to disclose details of the deal," a statement on the official BVB website said.
According to media reports, the transfer fee is believed to be in the region of seven million euros. No details about the contract length have been revealed.
Sahin rejoined Dortmund on an 18-month loan deal from Real Madrid in January 2013. The Turkey international had been on loan to Liverpool last season, but had failed to break into Brendan Rodgers' starting XI at Anfield, just as he had struggled at Real Madrid in the 2011-2012 season.
Sahin, a graduate of the Dortmund youth academy, has become a mainstay in BVB's midfield during the current campaign. He has played in every Bundesliga match, and all but one of the club’s Champions League matches.
The 25-year old has made a total of 179 Bundesliga appearances, making his first-team debut for Dortmund at 16 years old in August 2005, and is the youngest player to ever debut in the Bundesliga.
Sahin, who was born in Germany, has also been capped 44 times for Turkey.
Earlier this week, Dortmund announced the signing of Hertha Berlin attacker Adrian Ramos, 28. Media reports in Germany on Friday also link BVB with the versatile Freiburg defensive player Matthias Ginter.
The 20-year-old won his first cap for Germany in March 2014, and has also been linked with a switch to Borussia Moenchengladbach.
According to a report in Bild, the deal has already been made, but his current club SC Freiburg was quick to reject rumours of a done deal.
"We have neither received an offer by Borussia Dortmund nor have we held concrete talks," SC Freiburg sporting director Jochen Saier told kicker. "What has been reported is not true. There is nothing else to say."
"Nothing is confirmed," Ginter was quoted by kicker -- yet the paper confirmed Dortmund's interest in the young Germany international.
Dortmund beat Madrid 2-0 in the second leg of their Champions League quarterfinal on Tuesday, but it was not enough to overturn a 3-0 first-leg deficit. Los Blancos will now play Bundesliga champions Bayern Munich in the semifinals.