Updated

Branden Grace opened the World Match Play Championship with a 4 & 3 victory over defending champion Nicolas Colsaerts on Thursday.

Grace, a four-time titlist on the European Tour in 2012, was ahead by five at the turn before Colsaerts rallied with birdies on Nos. 10 and 12. The reigning champ's run ended shortly thereafter when he bogeyed the 14th, which allowed Grace to seal the result with a par on the next.

"I made a good birdie on the second hole, which was key to get off to a fast start, and then I think it was a 45-footer on the third hole which just kept the momentum going," said Grace. "It seemed I hit a good shot every time Nicolas hit a bad shot, which kind of opened the door for myself the first nine."

Colsaerts will now have to follow a familiar path, as last year the Belgian failed to win either of his first two matches before making it through to the weekend courtesy of a playoff decision over Charl Schwartzel.

World No. 8 Graeme McDowell was a 5 & 3 winner over Chris Wood, while 2011 champion Ian Poulter fell to Thailand's Thongchai Jaidee, 3 & 2, at Thracian Cliffs Golf & Beach Resort.

"To get the win under the belt today is very important to take the pressure off somewhat going into tomorrow, but you certainly can't take it lightly. If the game goes the other way in the morning, I still have a job to do tomorrow afternoon," said McDowell, who is playing his first European Tour event of the year after posting four top-10 finishes on the PGA Tour, including a victory at the RBC Heritage.

Carl Pettersson, who has rejoined the circuit in an attempt to qualify for the Ryder Cup, posted a 4 & 3 victory over Thorbjorn Olesen, while world No. 23 Peter Hanson and Francesco Molinari both posted a 2 & 1 victory -- over George Coetzee and Henrik Stenson, respectively.

Gonzalo Fernandez-Castano held off a hard-charging Jamie Donaldson to post a narrow 1-up win. The former held a 4-stroke lead with seven holes to play before the latter birdied the 12th and 14. Another birdie on the 16th reduced Donaldson's deficit to one, but the pair matched gains on the last, allowing Fernandez-Castano to hold on for the victory.

Bo Van Pelt, the only American in the field, and Richard Sterne managed the only halve of the opening day.

The remaining 16 group matches will take place Friday.

NOTES: The 24-man field is divided into eight groups of three players, with everyone playing two matches and the top two players from each group advancing to the single elimination matches on Saturday and Sunday ... Last year, Colsaerts defeated McDowell, 1-up, in the final.