Ian Poulter exited the World Match Play Championship in Bulgaria on Friday after losing by one hole to South Africa&aposs Thomas Aiken. The match swung back and forth with Aiken taking a two-shot lead on three occasions, but Poulter tied the game up before losing on the 18th hole after hitting his tee shot so far to the left it landed on an adjacent fairway. It was a crucial victory for Aiken, whose loss to Thailand&aposs Thongchai Jaidee by one hole in the morning session meant he had to defeat the Englishman to secure passage. Defending champion Nicolas Colsaerts put Thursday&aposs loss behind him as the Belgian registered a 3 and 2 win over Kiradech Aphibarnrat of Thailand. The triumph sets up a fixture with Gonzalo Fernandez-Castano of Spain in the last 16, after his 3 and 2 victory over Brett Rumford. Australian Rumford had earlier secured passage with a 5 and 3 victory over Welshman Jamie Donaldson. Northern Irishman Graeme McDowell coasted through to the last 16, defeating Scotland&aposs Stephen Gallacher 4 and 2. Gallacher was earlier beaten 2 and 1 by Englishman Chris Wood and finished bottom of the group. But there was a surprise for in-form Swede Henrik Stenson, who crashed out following a 3 and 1 loss to Felipe Aguilar, with the Chilean winning the last four holes to secure victory. In the morning session Aguilar came up short against Italian Franceso Molinari, who topped the group following his 4 and 3 victory. Former US Open champion Geoff Ogilvy had a disappointing day, losing 5 and 4 to South African Richard Sterne before halving his match with American Bo Van Pelt to crash out of the tournament. Peter Hanson of Sweden made it through despite a heavy 5 and 4 reversal to Shane Lowry. The Irishman was beaten by George Coetzee of South Africa 3 and 2 in the morning, but sill made it to the last 16. Scotland&aposs Scott Jamieson secured two victories after seeing off Sweden&aposs Carl Pettersson by one hole and Thorbjorn Olesen of Denmark 5 and 3. And South African Branden Grace secured the point he needed as he halved his match with Aphibarnrat.