Sam Stosur has been bundled out of the Tournament of Champions in Bali with a semi-final in sight after a straight sets loss to Spain's Maria Jose Martinez Sanchez.

Second seeded Stosur, who has reached a career high singles ranking of 13 this year, fired down seven aces but was weighed down by six double-faults in a patchy serving effort.

The 25-year-old broke her Spanish opponent twice in the second set but dropped her own serve three times to eventually go down 7-6 (7-4) 7-5 after a struggle of just over two hours.

Stosur was a late qualifier for the Bali field thanks to a title in Osaka, the first of her singles career.

Both women arrived in Bali at the last moment after competing in doubles at last week's WTA Championships in Doha.

Martinez Sanchez won the doubles title with Nuria Llagostera Vives, the seventh of the season, while Stosur and Rennae Stubbs lost in the semi-finals to Cara Black and Liezel Huber.

Top seed Marion Bartoli joined French compatriot Aravane Rezai in the semi-finals with a 6-3, 6-2 defeat of Shahar Peer of Israel on Friday.

Bartoli completed the weekend lineup at the $US600,000 ($A658,000) tournament comprising the 10 highest-ranking players who have won a WTA International title this year but who did not compete in the season-ending WTA Championships in Qatar, which finished Sunday. Two wildcards are also included.

Rezai, with a perfect 2-0 group record like Bartoli's, on Thursday was the first to reach the final four at this resort island.

Japan's Kimiko Date Krumm earned a place earlier Friday when Belgian Yanina Wickmayer quit on news of her one-year ban for missing doping tests.

Wickmayer, the world number 18, was suspended Thursday by the Flemish Doping Tribunal (VDT) for failing three times to fulfill the controversial "whereabouts rule."

Her withdrawal after the ban, which can be appealed at the Court of Arbitration for Sport (CAS) in Lausanne, put 39-year-old Date Krumm through. The Japanese veteran is the only Asian in the 12-woman field.