McIlroy's round fell apart after his birdie on the 5th hole that followed an eagle at the 4th, as he shot 42 in his back nine in glorious conditions at the Wentworth Club, southwest of London, on Thursday.

One over for his round arriving at the 17th tee, he pulled his drive and wound up making a double-bogey.

Another wayward drive led to a bogey at the 18th and he didn't talk to reporters after his round.

Wallace didn't drop a shot in his 65, also making eagle on the 4th to add to birdies at on the 1st, 5th and 6th.

The Englishman rolled in two more birdies coming home.

"I played the first seven or eight holes as good as I possibly could and showed my all-round game by grinding out the last few holes," Wallace said.

RIGHT: Wallace leads Henrik Stenson by one shot at Wentworth. PHOTO: Harry Trump/Getty Images.

Henrik Stenson was a stroke behind Wallace after a round of 66 that included an eagle on the 18th from a putt from off the green that took a horrible early bounce but still found the cup.

Fellow Ryder Cup player Jon Rahm joined Stenson in a tie for second place after birdieing four of his last five holes.

Paul Casey headed to the par-5 last hole on six-under, too, but made double-bogey to post a 68.

World No.4 Justin Rose recovered from a knee injury in time to start the tournament, which is staged at the headquarters of the European Tour, and birdied the 18th for a 67.

Australian Jason Scrivener is six shots off the lead after mixing three birdies with two bogies in his opening round 71.

Compatriot Scott Hend made par while fellow Australians Wade Ormsby and Lucas Herbert are battling to make the cut, sitting on two and three-over, respectively.

It is the first qualifying event for the European team for the 2020 Ryder Cup.