With current No. 1 Lee Westwood losing to Ian Poulter in Saturday's early last 16 tie, world No. 2 Donald or No. 3 Kaymer will replace the Briton if one of them goes on to win the championship at Finca Cortesin.

The semi-final will be a repeat of the world golf championship final earlier in the year, won by Donald, with the final taking place on the same day.

Kaymer is relishing the thought of getting the better of Donald this time and being top man in the world again.

"To become the number one again this weekend would be unbelievable," Kaymer told reporters. "On the other hand, Luke really deserves it as well.

"It will be a tough match and you have to make birdies to win holes because Luke doesn't make any mistakes." The German beat local favorite Alvaro Quiros of Spain in the quarterfinal by two holes.

Kaymer admitted to having a lucky break on the eighth when Quiros's ball hit a parked golf buggy and ricocheted into a bush, causing the big-hitting Spaniard to concede a hole he could have won.

Donald overcame US Masters champion Charl Schwartzel by the same score. He is expecting a tougher battle with Kaymer than he had when beating him 3 and 2 in the Tucson world golf championship final.

"I'm sure he has a little bit more in his tank than he did when I beat him at Tucson," Donald said. "I think it will be a close match." Belgian Nicolas Colsaerts is proving the surprise package of the week and the lowest ranked player in the competition disposed of US Open champion Graeme McDowell by 2 and 1 in their quarterfinal.

On Sunday Colsaerts will meet Poulter, who had beaten Westwood in the last 16 earlier in the day. Britain's Poulter then birdied the last three holes to overcome Italian Francesco Molinari by two holes in the last eight.