Nicolas Colsaerts, the defending champion, and former winner Ian Poulter face a battle to remain in the Volvo World Match Play Championship after losing their opening group games in Bulgaria yesterday.

Colsaerts was five down after just nine holes to South African Branden Grace before eventually losing 4&3, while Poulter started with three straight birdies at the spectacular Thracian Cliffs but also carded four bogeys and a double bogey in a 3&2 defeat to Thongchai Jaidee.

Ryder Cup team-mates Francesco Molinari, Graeme McDowell and Peter Hanson fared better with wins over Henrik Stenson, Chris Wood and George Coetzee respectively, while Carl Pettersson beat Thorbjorn Olesen, Gonzalo Fernandez-Castano saw off Jamie Donaldson on the 18th and Richard Sterne halved with Bo van Pelt.

The good news for Colsaerts and Poulter is that the three-man group format allows them the chance to reach the last 16 with a win today, with Colsaerts actually progressing via a play-off last year after drawing one game and losing the other.

"It's not often you lose in match play and everything is fine," said Poulter, who refused to blame stomach cramps for his surprise defeat.

"I got off to a great start with three straight birdies but made a few mistakes and gave him holes, which you don't do in match play. If you hit a couple of errant shots on this course you're going to struggle to get back."

Colsaerts was never in front against Grace, who holed from 45ft on the third for one of his five birdies on the front nine, but said: "I'm not worried because my game is so close to where it was the last two years. It's just about inches here and there.

In arguably the best game of the day, Fernandez-Castano beat Donaldson on the last when Donaldson looked like escaping with a half after being four down with seven to play. The Welshman birdied the 12th, won the 14th with a par and got back to one down with another birdie at the 16th after playing a recovery shot left-handed. He then hit a superb approach to six feet on the 18th, but Fernandez-Castano hit his even closer to seal the victory.

Biggest win of the day belonged to McDowell, who beat Wood 5&3 and will be assured of a place in the last 16 before his second match this afternoon if Wood also loses to Stephen Gallacher in the morning.