Ian Poulter was furious over an "inexcusable" error as he squandered a six-shot halfway lead in the Turkish Airlines Open and inadvertently kept the battle to be crowned European No 1 alive.

Seeking his first win for two years, Poulter completed a second round of 66 when the weather-affected event resumed on Saturday morning, taking his total for his last six rounds at the Montgomerie Maxx Royal to 33 under par.

However, the 38-year-old then struggled to a third round of 75 to end the day one shot behind Australian Wade Ormsby, who shot a 68 to finish 12 under par as he seeks his first European Tour title on his 200th appearance.

A three-putt bogey at the first was cancelled out by a birdie on the fourth, but Poulter then bogeyed the fifth and 11th before running up a double bogey on the 15th after his approach clattered into a tree short of the green.

"I'm most angry about the wedge shot which led to a double," lamented the Englishman. "That's inexcusable for me to make that error right there. A simple wedge shot puts me to 20 feet with an outside birdie look at worst, and I hit the tree, so I'm going to be angry about that for a little while tonight and then I'll be fine tomorrow.

"I'm going to get my head down and do the job tomorrow. Today was really disappointing to be out of rhythm after playing such great golf."

Lee Westwood carded a 67 to finish alongside Ryder Cup team-mate Poulter and Germany's Marcel Siem on 11 under, Siem's 66 reviving his bid to prevent Rory McIlroy winning the Race to Dubai for the second time in three years. Siem has to win in Turkey and at the season-ending DP World Tour Championship in Dubai to have any chance of overtaking world No 1 McIlroy at the top of the money list.

Ormsby's best finish this season is a tie for fifth in Morocco and the 34-year-old from Adelaide admitted: "It feels great to be in this position. It's a great tournament, great field. So to be up around the front is great and to be leading it makes me pretty happy. My game is good. I'm hitting it strong, putting good. But as good a score as I've shot, I still feel like I left a few out there. So I'll just keep trying to do what I'm doing and see how I end up."

Westwood had been eight shots behind Poulter after the second round, but was aided by holing his second shot to the seventh for an eagle as he charged up the leaderboard.

"It's been a while since I've been in contention, but generally when I get in contention, I know what to do," said Westwood, who won the Malaysian Open in April.

"I've been hitting the ball solidly for a few weeks. I haven't really played the par fives well enough the first couple of days. Today I played them a bit better. All in all, I'm pleased with where my game's at."

Siem, Jamie Donaldson and Sergio Garcia began the week as the only men who could catch McIlroy in the Race to Dubai and although Garcia carded a superb 65 to move to five under, BMW Masters winner Siem has the best chance to keep the battle going to the final week.

"It's more interesting now for everybody and I'll give it a shot tomorrow. That's what we are out here for, and there's why it's called Race to Dubai," Siem said. "I'll have a rest now and hope my ball-striking is as good as today and the putter is hot."