​Barcelona are holding up negotiations over Jasper Cillessen's exit this summer as they're holding out for a €25m transfer fee, but the club have already lined up Yann Sommer and Koen Casteels as potential replacements.

Back-up goalkeeper Cillessen has reportedly agreed on personal terms ahead of a move to S.L. Benfica this summer, with the Portuguese club looking to strengthen this summer as they look to win back to back titles next season.

Benfica are looking to reach terms over a €15m deal with Barcelona, but Goal report that the La Liga champions are holding up the transfer as they look for their €25m valuation to be met this summer.

Jasper Cillessen

Negotiations are still ongoing as both clubs look to reach a compromise, as Benfica are unlikely to agree to make Cillessen their new club-record signing, even if they decide to cash in on Portuguese wonderkid João Félix.

A list of replacements in Catalonia has already been drafted ahead of Cillessen's exit, and Spanish outlet Sport claim that Barcelona want to sign either Borussia Mönchengladbach goalkeeper Sommer or VfL Wolfsburg's Casteels as their new back-up for next season.

Both have been in fine form for their respective sides, but it's added that the club's first choice would be to bring in Sommer after he was considered as one of the top-performing goalkeepers in the Bundesliga this season.

Sport even claim that Sommer has an €11m release clause in his contract at Borussia-Park, although that's a figure which appears to have been plucked from thin air as a quick Google search will be able to tell you.

Yann Sommer

Both Bundesliga goalkeepers are tied to their respective clubs until 2021, with neither Wolfsburg or Gladbach being linked with any new goalkeeper signings.

Sommer even recently told Bild that he was excited to try and replicate Eintracht Frankfurt's success in next season's Europa League, suggesting that an exit this summer is unlikely.