Rory McIlroy will take an aggressive approach to try and rescue his US Open campaign after slumping to an opening 77 at Oakmont.

McIlroy completed his weather-delayed first round on Friday with bogeys at the last three holes to finish seven over par, equalling his worst ever score in the event which provided his first major victory in 2011.

The only good news for the 27-year-old was that Thursday’s early starters would not start their second rounds until Saturday morning, after initially being given a start time of 8:54pm on Friday evening — two minutes after sunset.

“It was hard yesterday to get into any sort of rhythm and when you are not in control of your swing it was compounded by being so stop-start,” said McIlroy, who carded eight bogeys and a solitary birdie.

“Right now I need to focus on hitting fairways and greens. I think I hit five fairways and eight greens which is not going to do anything. I hit irons off the tee on the first three holes and missed three fairways. With the course playing so soft I might just hit a lot more drivers and be as aggressive as I can.

“The toughest thing is trying to stay positive and not getting down on myself.”

McIlroy has never won a tournament in the United States after an over par opening round, but could take some encouragement from American Andrew Landry, the world number 624, shooting 66 to record the lowest first round in nine US Opens at Oakmont.

“You see guys shooting in the red and there are scores out there to be had,” the four-time major winner added. “You really need to be in control of your golf swing though and today, or over the last two days, I haven’t been.

“So I need to work on that, but there are low scores out there and if I’m able to get myself together I feel like I will be able to shoot one of those and I can stick around for the weekend at least. I need to shoot something like 66 in the next round to give myself any chance.”