Rory McIlroy conceded that he has lots of work to do ahead of next week's U.S. Open, admitting he is "concerned" about his form ahead of the third major of the year. 

McIlroy struggled with a new driver as he crashed out of the Canadian Open after shooting 78 in Friday's second round, slumping to the worst finish in his PGA Tour career.

The Northern Irishman finished nine-over par for the tournament to finish tied for 149th place, missing his first cut of the year and first since The Open at Royal Troon last year.

McIlroy was forced to change his driver after his previous model was deemed non-conforming in a random test on the eve of last month's PGA Championship. 

The 36-year-old went on to finish joint-47th in North Carolina, with the world number two still trying to find his rhythm and accuracy off the tee ever since. 

With a new 44-inch driver in hand, McIlroy found just 13 of 28 fairways in Toronto and he made a quadruple-bogey eight on the par-four fifth hole after a dismal tee-off.

Plenty of work to do for Rory McIlroy ahead of next week's US Open pic.twitter.com/0FGBl0E8Fg

— Sky Sports Golf (@SkySportsGolf) June 7, 2025

With play starting on 12 June, McIlroy has little time to iron out his issues from the tee as he aims to build on his Masters win in April, which sealed a career grand slam. 

McIlroy's first major title was at the 2011 U.S. Open at Congressional. He is the only player with a top-10 finish in each of the last six editions of the tournament. 

"Of course, it concerns me," said McIlroy. "You don't want to shoot high scores like the one I did today.

"I felt like I came here, obviously with a new driver, thinking 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. I'm still sort of searching for the missing piece off the tee.

"Obviously, for me, when I get that part of the game clicking, then everything falls into place for me. Right now that isn't. Yeah, that's a concern going into next week."

But the five-time Major winner says he will test several drivers in the coming days to find the right one.

"I'm going to have to do a lot of practice and a lot of work over the weekend at home and try to at least have a better idea of where my game is going into next week," said McIlroy.

"I went back to a 44-inch driver this week to try to get something that was a little more in control and could try to get something a bit more in play.

"But if I'm going to miss fairways, I'd rather have the ball speed and miss the fairway than not. I'd say I'll be testing quite a few drivers over the weekend."