Cameron Champ, making the most of his last-gasp entry as an alternate, seized the lead at the Canadian Open on Friday as Rory McIlroy crashed out of his last US Open tuneup.

Champ fired four birdies in a four-under-par 66 to seize a two-stroke lead at TPC Toronto Osprey Valley, where world number two McIlroy posted an eight-over 78 to miss the cut by a wide margin.

McIlroy, who won the Masters in April to complete a career Grand Slam, endured a horrendous day in a final start before next week's US Open at Oakmont.

McIlroy's nightmare round included a quadruple bogey eight at the fifth hole, where he fired his second shot out of bounds and after a one-stroke penalty hit another shot over the green.

He made a double-bogey at the 11th, where he was in the water hazard off the tee, and missed the cut for the first time this season.

"Of course it concerns me," McIlroy said. "You don't want to shoot high scores like the one I did today. "I came here obviously with a new driver thinking that that sort of was going to be good and solve some of the problems off the tee, but it didn't.

"Obviously going to Oakmont next week, what you need to do more than anything else there is hit fairways. When I get that part of the game clicking, then everything falls into place for me. Right now that isn't (happening). Yeah, that's a concern going into next week."

Meanwhile Champ posted his second straight bogey-free round, and while he said he didn't hit it as well as he did in Thursday's 62 his 12-under-par total of 128 was enough for a two-stroke lead over American Andrew Putnam, whose bogey-free 62 was the best round of the day.

Overnight co-leader Thorbjorn Olesen fired five birdies to balance three bogeys and a double bogey in an even par 70 to share third place on nine-under 131 with Canadians Nick Taylor and Richard Lee and Victor Perez of France.

Taylor the 2023 champion, posted a five-under 65 while Lee carded a six-under 64. Perez made four of his six birdies on the back nine on the way to a 65.

A joy to play

It's been a whirlwind trip north of the border for Champ, a three-time PGA Tour winner who lost his card last year and was preparing to play in the Korn Ferry Tour event in South Carolina when he found on Tuesday he'd made the Canadian field as eighth alternate.

"Luckily I actually brought my passport," Champ said. "I don't know why I brought it. I was like, you know, I'm just going to bring it in case for whatever reason, not even thinking about the tournament."

Not only did Champ take the schedule shake-up in stride, he embraced the opportunity after a couple of years in which "off course stuff" had made it "a little rough for me to even be out here.

"I just finally kind of accepted that and finally got some help," Champ said after a round that featured two birdies on each side. "For me, it's just a refresher to kind of be free in a sense ... I could care less what I shoot.

"These last two days, it was just a joy for me to be able to play like that."

Chile's Cristobal Del Solar, who flirted with a 59 before joining Olesen in shooting 61 on Thursday, carded a one-over 71 and was among a group of six on eight-under 132 that also included Ireland's Shane Lowry.