Zenden started as the Dutch racked up three goals before half-time to maintain their 100 percent record in Group Three.
But he was forced to hobble off after 70 minutes, and though the extent of the problem is not yet known, Zenden fears a lengthy spell on the sidelines.
"Nothing is broken and I also think that nothing is torn off," he said. "But I have lots of pain and can hardly stand on the foot. I'm afraid that I will be out for Chelsea for a few weeks."
Zenden, a £7.5million signing from Barcelona just over a year ago, has been a mor regular fixture in the Blues side this season after a stop-start first Premiership campaign.
If his diagnosis proves correct, the Dutchman could miss Chelsea's forthcoming games against newly-promoted duo Manchester City and West Brom.
stevefurlong@chelsea-mad.co.uk
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