Frenkie de Jong says he is "disappointed" after being ruled out of Euro 2024 with an ankle injury.
Following the Netherlands' 4-0 thrashing of Iceland on Monday, it was confirmed in a social media post that the midfielder would not recover in time to play in the tournament.
De Jong has not played since Barcelona's Clasico defeat to Real Madrid on April 21, though still got a place in Koeman’s final 26-man squad despite his injury.
He has emerged as a fixture in the Netherlands' midfield since making his senior international debut in 2018, earning 54 caps and scoring two goals.
Following his withdrawal, De Jong said on Instagram: "I'm sad and disappointed that I won't make it to the European Championship.
"We've been doing a lot of it the past few weeks, but my ankle needs more time, unfortunately.
"It's a dream and greatest honour to represent our country in a final tournament. Wearing the orange shirt, singing the Wilhelmus and feeling the support of the entire country.
"But now I will, like the entire orange legion, cheer for our team from the sidelines. Let's go, boys."
In his post-match press conference, Koeman hit out at Barcelona for the way they handled De Jong's injury, saying they were "left with nothing" after his former club took a risk with the player.
In a later interview on Dutch television, he admitted he knew about the withdrawal hours before kick-off and informed the rest of the squad before their game against Iceland.
"Tests have shown that he cannot yet do what he should be able to do. He gets a reaction from his ankle every time after training," Koeman said.
"Then you have to conclude that he will not be 100 per cent fit for the next three weeks. I already thought that playing against Poland [in the Group D opener] would be difficult."
The Netherlands also suffered an injury scare during the game as Teun Koopmeiners suffered a thigh injury in the warm-up, forcing him to withdraw from the starting line-up.
They face Poland in their Group D opener in Hamburg on Sunday, before taking on France and Austria in their other group matches.