Barcelona have signed Turkey midfielder Arda Turan from Atletico Madrid for an initial fee of £24m.
The Spanish champions said the deal for the 28-year-old could reach £29m with potential add-ons.
Turan will not be able to play for the club until January as Barca are unable to register new players until 2016 under the terms of a Fifa ban.
He scored 22 goals and provided 32 assists in four seasons with Atletico after joining from Galatasaray in 2011.
Barca were banned from signing players in 2015 after being found guilty of breaching Fifa's rules on the transfer of players aged under 18.
The signing of Turan, who has played 81 times for Turkey, is also complicated by their ongoing presidential election campaign.
In the absence of a president, the Catalan club are being administered by a special commission, which had to approve the transfer.
The commission included an unusual clause which means whoever wins the July 18 election has an option to sell Turan back to Atletico within two days for 10% less than the initial £24m outlay.
Luis Enrique's side - who won La Liga, the Copa del Rey and the Champions League last season - have also signed winger Aleix Vidal for £16m from Sevilla this summer.
Find all the latest football transfers on our dedicated page.