Amsterdam - The Netherlands will be a much weaker force without an injured Arjen Robben when they play Latvia in a key UEFA 2016 qualifier next month, conceded coach Guus Hiddink.
"With the absence of Arjen Robben, the team will lose 30 to 40 percent of its quality and production. That's the impact he has shown over the last year and a half.
"It's a loss for the Dutch national team, but also very annoying for him and Bayern Munich. I can complain about it long and hard, but that will not help. We must go on," Hiddink told Wednesday's edition of the Dutch daily newspaper De Telegraaf.
Robben recently recovered from an abdominal muscle injury only to suffer a calf tear, which has ended his season. He was missing for Bayern over the two legs of their Champions League semi-final loss to Barcelona over the last seven days.
The Dutch play Latvia away in Riga on June 12. They beat Latvia 6-0 in Amsterdam in October with two goals from the 31-year-old but without Robben, lost to Czech Republic last September and were held at home by Turkey in March.
The setbacks means the Netherlands trail the Czechs and Iceland in the Group A standings. They have seven points from five matches to 13 for the Czech Republic and 12 for Iceland, who upset the Dutch 2-0 in October.
Hiddink said he believed Robben would be back to form next season.
"I'm not worried, because he is so driven and he is conditionally strong. In terms of body and spirit he can last."
The Dutch also meet the United States in a warm-up friendly at home on June 5 without Robben.