BASEL, Switzerland -- Stanislas Wawrinka's prospects of playing in his first ATP World Tour Finals were damaged Tuesday by a 6-4, 6-3 first-round loss to Edouard Roger-Vasselin at the Swiss Indoors.
Second-seeded Tomas Berdych of the Czech Republic also lost, 4-6, 7-6 (4), 7-6 (2) against big-serving Ivo Karlovic of Croatia, to open up Roger Federer's half of the draw.
Karlovic sent down 23 aces and did not need to break Berdych's serve to clinch victory.
Wawrinka, ranked No. 8, struggled with his service, landing barely one-third of his first serves, to continue his struggles in home tournaments in Switzerland.
For 29-year-old Roger-Vasselin, it was a first victory against a top-10 player this season and just the second of his career.
Wawrinka, a U.S. Open semifinalist last month, is eighth in the points race to secure a place in the eight-man finals lineup in London next month.
The ninth-placed player after next week's Paris Masters will advance, because Wimbledon champion Andy Murray has ended his season following back surgery.
While Berdych is sixth and likely to qualify, Wawrinka is under pressure from Frenchmen Jo-Wilfried Tsonga and Richard Gasquet, who begins in Basel on Wednesday against countryman Michael Llodra.
Wawrinka, seeded No. 4, has now lost his opening match at Basel to a lower-ranked opponent in three of his past five visits.
Berdych lost his first-round match at Basel for the fourth straight time, all against opponents ranked below him.
Seventh-seeded Andreas Seppi of Italy also lost Tuesday, 7-6 (3), 6-3, against Daniel Brands of Germany, who beat Federer at the Swiss Open in Gstaad in July.
Federer, third-seeded this week, will play his second round match Wednesday against Denis Istomin of Uzbekistan, who beat Horacio Zeballos of Argentina 7-5, 7-6 (3).
Kei Nishikori, the No. 6 seed from Japan, eased past Swiss wild card entry Marco Chiudinelli 6-2, 6-4.
Marcos Baghdatis of Cyprus beat German qualifier Benjamin Becker, 7-6 (8), 6-1, and Ivan Dodig of Croatia advanced after winning just two games when Carlos Berlocq of Argentina retired injured.