Kluivert had scored Bournemouth's first-ever European goal in Anoeta, but picked up an injury, manager Marco Rose revealed on Sunday.
"Justin suffered an injury in San Sebastian. We're gonna miss him for some weeks. Nothing real bad, but it needs time," Rose said.
The injury will cost Kluivert the upcoming UEFA Nations League games with the Netherlands, where Xavi will make his debut as Oranje manager against Germany on September 24th.
It is not yet known who'll replace the midfielder. Luciano Valente (Feyenoord), Kees Smit (AZ), and Guus Til (PSV) are the likeliest options to replace the 14-time international.
Kluivert was part of the Netherlands' 2026 FIFA World Cup squad last summer, but played just 22 minutes after missing most of 2026 with a knee injury. The Bournemouth star was called up for Xavi's first Netherlands squad last week.