Northern Irishman Graeme McDowell booked his place in the semi-finals of the World Match Play Championship in Bulgaria on Saturday. McDowell will be joined by South African pair Thomas Aiken and Branden Grace, and Thailand&aposs Thongchai Jaidee in the last four after the quartet enjoyed good days at the Thracian Cliffs Golf & Beach Resort in Kavarna. On a day in which all round of 16 and quarter-final matches were played, 2010 US Open champion McDowell was most impressive at the European Tour event. The world number eight begun his day with a one-hole victory over American Bo Van Pelt, which came thanks to a superb start. McDowell won four of the first five holes and built up a significant advantage, which was enough to see him home despite a strong finish from his opponent. The 33-year-old then edged defending champion Nicolas Colsaerts of Belgium 2 and 1 in their quarter-final. Colsaerts took an early lead but McDowell won four holes between the fourth and the eighth to again move well ahead. The loser who was team-mates with McDowell at the 2012 Ryder Cup – responded in good fashion but his opponent&aposs win on hole 17 saw him claim a terrific win, setting up a semi-final against Grace. Grace started with a comfortable 4 and 3 triumph over Australian Brett Rumford before he toppled Englishman Chris Wood 2 and 1. Aiken had to go to a play-off hole to edge Irishman Shane Lowry in the round of 16 and he backed that up with a 3 and 2 success against Italy&aposs Francesco Molinari. Jaidee&aposs route to the semi-finals saw him defeat Swede Peter Hanson in 21 holes before he cruised past Scotsman Scott Jamieson 4 and 3 to secure a berth in the last four. Aiken will play Jaidee in Sunday&aposs other semi-final, before the decider is contested.