Transfer market wheels keep on turning as European teams scramble to get new acquisitions.

The end of Iker Casillas's 25-year affiliation with Real Madrid drew near on Monday when news that the goalkeeper is interested in Porto was broken by his agent. The Portuguese club submitted a formal bid for Casillas.

"Iker is interested in Porto and Porto are interested in Iker. We hope Madrid facilitate his departure," agent Carlo Cutropia told Portuguese media site Record.

Madrid has not accepted the bid as of this writing but they are committed to moving their captain Casillas to another team this summer, Spanish TV station TVE reported, as translated by Daily Mail UK. Real has been continuously pursuing Manchester United goalkeeper David de Gea, not only to acquire a new addition to the team, but also to encourage the captain to depart Real. Real has struggled to find a way to make moves toward that goal, as few clubs expressed interest in acquiring the 34-year-old player for a significant amount of money.

Real had agreed with Casillas that they will ensure that his salary remains around the same amount, even when the Bernabéu needs to fill the gap, noted ESPN. The captain currently makes €7.5 million ($8.2 million) with the Spanish football club.

The Spanish star initially preferred to have the final two years of his contract paid in full and enter free agency. Madrid held off, and Porto entered the negotiations hopeful that costs will not be outrageous.

"Iker is very interested in going to Porto," Cutropia told Record. "Madrid have an offer and they know what Casillas wants."

The goalkeeper is also currently the captain of the Spanish national football team, for which he made 162 appearances and won two European Championships and the 2010 FIFA World Cup.

Barcelona signs Arda Turan

Meanwhile, FC Barcelona has signed Turkish midfielder Arda Turan from Atletico Madrid in an initial fee of £24 million. The Spanish champs said the deal for Turan could reach a final total of £29 million after all negotiations, ESPN reported.

Despite the signing, Turan will be unable to play for Barça until January as compliance to the terms of a FIFA ban.

Barça was banned from signing players in 2015 after being found guilty of breaching the league's rules that pertain to the transfer of players under 18 years old.

Turan registered 22 goals and 32 assists in four seasons with Atletico since 2011.

The deal is complicated by the campaigns for FC Barcelona president. In the absence of a head, the Catalan club is being administered by a special commission, who has yet to approve the transfer.