Rory Mcilory and Tiger Woods both lost their opening round matches at the Turkish Airlines World Golf Final.
Rory Mcilroy dropped seven shots in three holes to lose to Matt Kuchar, while Tiger Woods lost on the 18th to Charl Schwartzel.
Mcilroy shot 34 on the front 9 including two eagles, yet a succession of triple bogey, double bogey, double bogey from 15-17 gifted the match to Kuchar.
Tiger's match with South African Schwartzel was a tighter affair. He shot birdies on 16 and 17, meaning the pair went down the last hole all square. Yet a poor approach shot from Woods resulted in a bogey, Schwartzel winning with a par.
Justin Rose shot a level par 71 to ease past American Hunter Mahan who himself shot a four over par round.
The final pairing saw another Europe - America clash with Lee Westwood taking on Webb Simpson. The British World Number 4 scored a one over par 72 which was good enough to take victory, with Simpson carding a three over par.
Each of the eight players will play two more matches in the group stages, both tomorrow.
The winner of Group One will then face the runner-up of Group Two, and vice versa, in Thursday's semi-finals, with the final to be staged on Friday.
Mcilroy and Woods play each other tomorrow afternoon, but if either player loses their morning match they will be out of the £3.2 million event before the world's top two meet.