Borussia Dortmund's Marco Reus (L) scores a goal against Real Madrid's Iker Casillas during their Champions League quarter-final second leg soccer match in Dortmund, April 8, 2014.
Iker Casillas is likely to move to Porto, according to his agentReuters

Iker Casillas's agent, Carlos Cutropia, has said the Real Madrid legend is likely to move to Porto during the summer transfer window amid the expected arrival of David de Gea from Manchester United to be Rafa Benitez's first-choice goalkeeper next season.

The Real Madrid vice-captain had insisted on a number of occasions that his desire was to hang up his boots at the Santiago Bernabeu despite having fallen out of favour with his own fans in recent seasons.

But with the club having earmarked De Gea as a priority for the summer, Spanish TV station RTVE reported that Casillas has changed his mind and has decided to continue his career at Porto.

The Spanish TV channel claimed that even though an agreement has not been reached, all parties were in favour of reaching a deal, pointing out Casillas's exit means an "essential step in De Gea's move to Real Madrid".

The agent of the 'keeper has confirmed the news while hoping an agreement between the clubs is sorted to see Casillas playing for Porto next term.

"There's an offer from Porto and Casillas is excited by the prospect. Now we'll have to wait and see what Real Madrid say," Cutropia said to Marca.

"Iker is very enthusiastic about the possibility of going to Porto. Real Madrid have the offer and know what Casillas wants. Right now we're trying to come to an understanding."

According to Marca, Real Madrid are likely to let him go for free, so the only stumbling block in the negotiations is the fact that Casillas still has two years remaining on his contract at the Bernabeu.

Porto are unable to meet his wages in full so the 'keeper is negotiating the possibility that the Portuguese side and Real Madrid share his salary in order to avoid losing the money he would earn in case he stays at the Santiago Bernabeu for the remainder of his contract.

Meanwhile, the Spanish publication claimed on 6 July that De Gea asked United manager Louis van Gaal once again to let him move to Real Madrid during the summer transfer window and Los Blancos will need to pay around €40m (£28.3m, $44.1m) to secure the deal.