Spain's Jon Rahm can become world number one for the first time with victory in the Waste Management Phoenix Open - and a little help from Brooks Koepka.

Rahm will climb from third in the standings to first if he claims a fourth PGA Tour title at TPC Scottsdale and current number one Koepka finishes worse than outright fourth in the Saudi International.

The late Seve Ballesteros is the only Spanish player to have been world number one, the five-time major winner spending a total of 61 weeks at the summit across five different spells.

Rahm, who finished runner-up in the Farmers Insurance Open last week, will play alongside Justin Thomas and Hideki Matsuyama in the first two rounds in Phoenix, where Rickie Fowler will defend the title he won in dramatic fashion last year.

Fowler looked set to squander a five-shot lead with just eight holes to play when he chipped into the water on the 11th and then - after taking a penalty drop and walking away to survey his next shot - saw his ball roll back into the hazard.

After a discussion with PGA Tour rules official Slugger White, that meant another penalty drop and in the end Fowler did remarkably well to chip to 15 feet and hole the putt for a demoralising triple-bogey seven.

It was no surprise that Fowler bogeyed the next and found himself a shot behind a charging Branden Grace, but Fowler drew level with a birdie on the 15th before it was Grace's turn to implode by driving into the water on the short par-four 17th.

Grace compounded the error by chipping into a greenside bunker and did well to salvage a bogey, but Fowler then drove the green on the same hole and two-putted from 55 feet for a decisive birdie.

A par on the last gave Fowler a closing 74 and a two-shot victory over Grace, with Thomas a shot further back.