Jon Rahm toils as Rory McIlroy battles hard in opening round of US PGA Championship at Oak Hill Country Club

Masters champion Jon Rahm found it tough going in the opening round of the US PGA Championship, as Rory McIlroy battled to keep his hopes alive.

The Spaniard made a superb start with a birdie on his opening hole, his 10th, and was solid for six holes.

But from the 16th, his seventh, the round unravelled for the world No. 1. He went on a run of five bogeys in six holes to drop off the pace.

A double bogey saw Rahm drop to seven-over, but he made an excellent birdie on his penultimate hole to sign for a 76.

McIlroy’s round was in danger of going the same way as Rahm’s, but he showed tremendous resolve on a day when he struggled off the tee.

After being one of the form players heading into the opening major and being full of confidence about completing the career Grand Slam, things have gone south since a missed cut at Augusta.

McIlroy returned to action at the Wells Fargo Championship and failed to figure. Worryingly, he was battling a two-way miss which is a golfer’s worst nightmare.

In the opening round of the second major of the year on Thursday, he hit only two of 14 fairways but somehow scrambled superbly around a course with penal rough.

McIroy dropped to three-over at one stage, but after putting in for par from off the green on his 12th hole he gained some momentum.

Three birdies and a further bogey followed in a round of 69, as McIlroy kept himself in the tournament.

Scottie Scheffler is the other member of the current big three in golf, and McIlroy and Rahm find themselves four and nine shots respectively behind the American who set the early clubhouse lead with a round of 67.