Chelsea took a gargantuan loss on Kepa Arrizabalaga after the goalkeeper joined London rivals Arsenal on Tuesday.

The deal was worth just £5 million after Arsenal triggered the goalkeeper's modest release clause, according to BBC Sport's Nizaar Kinsella.

Kepa remains the world's most expensive 'keeper after he joined Chelsea from Athletic Bilbao for £72 million in 2018. The 30-year-old spent last season on loan at Bournemouth.

The Spaniard will compete with compatriot David Raya to be Arsenal's starting goalkeeper.

"I think we are so close to winning and, hopefully, altogether, we can achieve it," Kepa said in an Arsenal statement.

Kepa won the Champions League, Europa League, UEFA Super Cup, and Club World Cup while making 163 appearances for Chelsea. Despite his successes, his spell in west London was blighted by errors and rampant criticism.

His lowest ebb with the Blues was perhaps during his debut campaign when he appeared to refuse his substitution near the end of extra time of the 2019 League Cup final. He then failed to lead Chelsea to victory over Manchester City in the shootout as backup 'keeper Willy Caballero, who had a strong track record of saving penalties, watched on from the bench.

Kepa finished as a runner-up in three FA Cup finals and two League Cup finals with Chelsea.

Kepa was on loan at Real Madrid the season before his Bournemouth stint. He played 20 times across all competitions for Los Blancos and won the Champions League, La Liga, and the Supercopa de Espana.

He's earned 13 caps for Spain.

"We are really happy to have Kepa joining us," said Mikel Arteta. "He brings a wealth of experience, which his teammates will benefit from, and he has a real hunger to win."