World number one Dustin Johnson declared himself ready to challenge for victory after a tidy return to competition left him four strokes behind first-round leader Francesco Molinari at the Wells Fargo Championship on Thursday.

World number one Dustin Johnson's participation in the US Masters this week is in doubt after he injured his back in a freak accident, his manager David Winkle said on Wednesday.

Rory McIlroy believes he will carry a psychological edge into his duel with Gary Woodland after being drawn to face the American in the opening round of the World Golf Championship-Dell Match Play tournament on Monday.

Patience will be a virtue for Rory McIlroy on Sunday as he seeks to win the WGC-Mexico Championship and possibly regain the world number one ranking.

Rory McIlroy, chasing a return to the world No. 1 ranking in his first start in seven weeks, fired a second-round 65 on Friday to grab the lead in the WGC-Mexico Championship.

Dustin Johnson made the complicated world golf ranking calculations simple on Sunday, vaulting to number one with a convincing victory in the Genesis Open.

World number two Dustin Johnson, who won his first major title at the US Open Golf Championship in June, will not play in the Rio Olympics because of concerns over the Zika virus.