Rory McIlroy hit US Open mode two weeks early when he opened with a bogey-free 66 in the RBC Canadian Open.

As Leona Maguire battled to a three-over 73 and amateur Aine Donegan posted a 76 in the US Women’s Open, where world number one Nelly Korda’s hopes evaporated when she made a septuple bogey ten in an 80, McIlroy was thrilled to grind out a clean card just two weeks before heading to Pinehurst No 2.

The world number three played his front nine nine “blind” and had to make five par putts between four and seven feet just to turn in level par.

But he found his groove with four back-nine birdies, including three in his last four holes, to post a 66 that left just four shots behind David Skinns, who shot 62 late in the day to lead by a shot from Sam Burns and Sean O’Hair.

“I only played the front nine in the pro-am, so I was happy enough to get out of there in even par and not make a bogey,” McIlroy said. 

“But once I got that nine holes out of the way I knew there were some chances on that front side. Four birdies there, no bogeys was a good day's work.”

Playing his ninth event in 12 weeks and the first of a four-in-a-row run, he feels he’s finally producing cleaner cards.

“At the start of the year, or at least through February, March, and April, I was making some big numbers, and there was a lot of volatility on the scorecard,” he said. “But to play bogey-free rounds is really nice again.

“I felt like I got some good practice on the front side there just trying to save par the whole time, getting a lot of practice on my six-footers… Hopefully, I can keep that going the next few days.”

Seamus Power and Shane Lowry are tied 95th after 72s, leaving them with work to do to make the cut today.

But while a three-over 73 left Maguire outside the top 80 when she posted her card in the US Women’s Open at Lancaster Country Club in Pennsylvania, she was up to tied 35th, only five shots behind leader Yuka Saso by day’s end.

Saso shot 68 to lead by a shot from French amateur Adela Cernousek, who won the recent NCAA Championship, Thailand’s Wichanee Meechai and American Andrea Lee.

The big shock was Korda’s opening 80, which dashed her chances of winning for the seventh time in eight starts.

The world number bogeyed at the 10^th (her first), then put three balls in the water at the 161-yard 12th en route to a septuple bogey 10.

“I'm human,” Korda said after a level par back nine. “I'm going to have bad days. I played some really solid golf up to this point. Today was just a bad day.”

As for the Irish, Maguire bogeyed the second and third but made a birdie two from four feet at the 160-yard sixth before getting up and down from 40 yards for par at the 205-yard eighth.

She turned for home in one-over but dropped two shots coming after bunkering tee shots at the 10th and short 17th.

Stephanie Meadow withdrew, citing illness shortly before her afternoon tee time, but with the 6,500-yard course playing tough, Maguire was not out of it by any means.

As for Lahinch amateur Donegan, she followed a bogey at the fourth with a birdie from 29 feet at the fifth before missing a six-footer for a birdie at the sixth.

But while she double-bogeyed the par-five seventh, then bogeyed the eighth before following par saves at the ninth and 10th with three bogeys in her last five holes, her 76 still gives her a chance to make the cut.

A total of 35 putts told a tale for the Ennis native, who was tied for 96th with LSU teammate Latanna Stone and one shot better than her other teammate, world number one amateur Ingrid Lindblad.

Meanwhile, Tom McKibbin made a fast start to his defence of the fog-delayed European Open at Green Eagle Golf Courses in Hamburg.

The Holywood star (21) followed an opening bogey with birdies at the fourth, ninth, 11^th, 17^th and 18^th to open with a four-under 69.

He was joint fourth, five behind Germany’s Jannik De Bruyn, whose 64 gave him a four-shot lead over England’s Laurie Canter and Wales’ Jack Davidson.