French third seed Jo-Wilfried Tsonga suffered a shock 7-6, 4-6, 6-4 defeat by Dutch wildcard Igor Sijsling in the first round of the World Indoor Tournament on Monday.
The 27-year-old Tsonga squandered five breakpoints before surrendering the first set 7-3 in the tiebreak but appeared to have gained control of the match when he levelled the contest at one-set all.
"I can't say I played bad tennis but on this kind of surface matches are always tight," Tsonga, the highest seed in action on Monday in a tournament headed by Roger Federer, told reporters.
"It is disappointing to drop out early at such a big tournament."
Tsonga's compatriot Gilles Simon eased past German Daniel Brands with a 7-6, 6-4.
Both players dropped their serve twice before Simon clinched the tiebreak and won the second to set up a second round match with Italian qualifier Matteo Viola.
Photograph: Dean Mouhtaropoulos/Getty Images
Give me more time before judging me, says Nadal
Chelsea discard Di Matteo after Juventus defeat
Janowicz polishes off Simon to reach Paris final
i-Shakti's brand dilemma
Women's 'hormones' behind lack of consistency: Tsonga