Real Madrid target Kiko Casilla cannot snub once-in-a-lifetime offer - Espanyol

Espanyol coach Sergio Gonzalez will be sad to see goalkeeper Kiko Casilla leave but believes the player should not turn down a potential move to Real Madrid this summer.

The Spanish giants must reinforce their back line following the departure of Iker Casillas to Porto, and Spanish sports newspaper AS reported on Thursday that 28-year-old Casilla is on the verge of joining Real, his former youth club, in a €6 million deal.

Espanyol turned down a €4m bid from Real last week for Casilla, and told Los Blancos to make a substantial increase in their offer to have a chance of acquiring the Spaniard.

"Real Madrid is a historic opportunity for the player, a once-in-a-lifetime [chance]," Gonzalez said as reported in El Mundo Deportivo. "It's an opportunity to join a top level team that you have to take with your eyes shut.

"You cannot turn it down because you are going to a No. 1 club. At least this is how I see it, having experienced this but at a different level."

Gonzalez, a former Spain international, played for nine seasons at Deportivo La Coruna having previously featured for Espanyol.

Casilla left Real in the summer of 2007 to join Espanyol, and is under contract with the Barcelona-based club until June 2018.

The keeper, who has a release clause set at €20m, started in 37 league games for Espanyol in 2014-15 and kept 13 clean sheets.

"I cannot put a price on my players because for me, they have an inestimable value but as always, in football, you are exposed to this type of numbers," Gonzalez said. "[Casilla] is still ours until something happens."

Gonzalez will not fret if Espanyol do sell Casilla because his understudy will still be with the team, saying: "We nevertheless have full confidence in Pau Lopez."

Gonzalez praised Casilla for the attitude he has shown despite the ongoing speculation regarding his future, continuing: "Any other player seeing this opportunity would have forced the situation much more.

"Espanyol is very lucky to have him. He is a serious professional. At no time has he asked me to stop training and he is very enthusiastic, as though nothing was going on."

The bigger issue for Real fans is if and when the club will sign Manchester United goalkeeper David De Gea.

Real coach Rafa Benitez has not spoken of his team's ongoing search for a new goalkeeper, although it is widely reported that Los Blancos are keen to acquire De Gea and that negotiations have stalled between the clubs.

The Spanish giants, who are on their summer tour of Australia, only have third-choice keeper Pacheco and Castilla youngster Ruben Yanez in goal following the departure of Casillas, with Keylor Navas sidelined by injury.

Benitez has spoken for the first time since the exit of Casillas, saying on the club's official website: "Iker is a living legend at Real Madrid and the best goalkeeper in the club's history.

"We all know how important he has always been. He has made the decision to leave and to go to another club. As coach, I have to respect that decision and wish him the very best of luck."