The Dutch still have a mathematical chance of reaching Russia if they beat Sweden in Amsterdam on Tuesday but admit that the seven-goal victory margin needed to leapfrog their opponents is highly unlikely.
"It caused me a lot of pain but unfortunately that is part of sport," said the Bayern Munich winger, who after 95 caps is edging ever closer to the end to his international career.
Saturday's result left the Dutch on 16 points from nine matches in Group A, three behind second-placed Sweden, who have a vastly superior goal difference of plus-19 compared to plus-six for the Netherlands.
Sweden's 8-0 home demolition of Luxembourg on Saturday was a crushing blow, said Robben. "We couldn't believe it was that much," he told Dutch television.
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Sweden had completed their victory by the time the Netherlands took to the field in Borisov, where Robben scored one goal and made another in the victory.
"After the result in Sweden we could not do much more than come out with our chests out. But to win 8-0 in Belrus was never going to be realistic. And 7-0 at home against Sweden, that's not going to happen either.
"Obviously we must keep believing until the last minute but I had better say what everyone is thinking. It is not realistic to think we can beat Sweden with a big score. People had best leave their calculators at home." As to his own future with the national team, the 33-year-old Robben said: "First Sweden and then we'll see."
Missing out on the World Cup continues a dramatic fall from grace after the Dutch were runners-up in South Africa in 2010 and third at the last tournament in Brazil.
They failed to qualify for the European Championship in France last year and now appear virtually certain of being absent for a second major tournament in succession.
(Reporting by Mark Gleeson; Editing by John O'Brien)
