Australian Jason Day beat an ailing Louis Oosthuizen to move into the semi-finals of the WGC-Accenture Match Play Championship on Saturday, as Graeme McDowell enjoyed a unique experience at Dove Mountain.
Oosthuizen received lengthy treatment for a long-standing back injury before play started and needed more out on the course before eventually losing 2&1 to Day, who reached the last four for the second year running.
Former Open champion Oosthuizen looked to be in real trouble from the outset as he carved his opening tee shot into the desert. After attempting to hack clear from a bush, Oosthuizen quickly conceded the hole and seemed likely to fall two down after another errant drive on the second.
However, this time the South African took a penalty drop and then hit a superb third shot with a fairway wood on to the green, holing the putt from 20 feet for an unlikely winning birdie.
Another birdie on the third briefly took Oosthuizen one up, but he made a mess of the fourth with two bad pitches and went behind to a Day birdie on the fifth.
Day won the ninth and 11th to move three up, but Oosthuizen continued to battle hard, winning the 13th and halving the 14th and 15th with birdies, but Day held on to seal victory.
McDowell had played 58 holes to reach the quarter-finals and had remarkably never stood on any tee with the lead, producing miraculous comebacks to edge past Gary Woodland, Hideki Matsuyama and Hunter Mahan.
But the former US Open champion needed just two holes to finally get his nose in front against Victor Dubuisson, a conceded eagle on the par-five second taking him one up and also leaving the Frenchman facing a deficit for the first time this week.
McDowell went further ahead with a birdie on the third, but Dubuisson birdied the fourth and seventh to get back on level terms.
Elsewhere, Jim Furyk was producing a brilliant turnaround in his match with Rickie Fowler, who had looked like progressing to the last four when he went three up on the 11th.
However, Furyk then birdied the 13th, 14th and 15th and won the 16th with a par to move one ahead with two to play.
In the remaining match, Ernie Els was one up after 10 against rising star Jordan Spieth.