By Mark Lamport-Stokes

OAKMONT, Pennsylvania (Reuters) - Rory McIlroy left himself with plenty of work to do to make the cut at this week's U.S. Open after struggling to a seven-over-par 77 in the weather-delayed opening round on Friday.

The Northern Irish world number three said he had not been in control of his golf swing while piling up eight bogeys and a lone birdie on the tough Oakmont Country Club layout and would need to shoot "something like 66" in the second round.

"You see guys shooting in the red - there is a 66, a 67 – so there are scores out there to be had," four-times major winner McIlroy told reporters after finishing a distant 11 strokes off the early pace set by American rookie Andrew Landry.

"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," said McIlroy, who bogeyed five of his last seven holes on one of the toughest courses in golf.

"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."

McIlroy, who claimed his first major title with a stunning eight-shot victory in the 2011 U.S. Open at Congressional, said the multiple weather delays on Thursday due to thunderstorms had been a test of patience and time management.

"It's been tough," said the 27-year-old, who is scheduled to start his second round on Saturday as organizers try to get the tournament back on track. "It's a long first round, it's taken us over 24 hours to complete it.

"I've got a lot of time now between now and going back out there so I will rest up a bit ... come back out here this evening, hit a few balls and try to figure out what the problem is with my swing.

"Even walking the last few holes, I was thinking, 'Do I go to the range straightaway, or rest and come back later?' (The delays) have definitely complicated matters a little bit, but when you shoot 77 everything is a bit complicated."

(Editing by Larry Fine)