Rory McIlroy might have been utterly frustrated to drop two shots late in his round but a three under 67 was still good enough to leave the world No 1 tied for the lead after the opening round of the BMW Championship in Denver.

Ranked second in the FedEx Cup standings but the clear favourite to run away with the $10m bonus awarded after the Tour Championship, the 25-year old looked head and shoulders above the opposition at altitude at Cherry Hills Village.

But while his booming drives and his usual array of laser-like iron shots were impressive, it was a par save at his 14th hole that stood out like a beacon.

Buried in the deep rough that's needed to protect scoring, McIlroy was short right on a steep sidehill lie on the 526-yard, par-four fifth.

With the ball well above his feet, he faced with a 25 yard pitch to an elevated green, gripped down almost to the metal and fed the ball down to eight feet above the hole before slotting home the putt.

"Yeah, it was a brutal lie, and I was just trying to get it somewhere on the green," McIlroy said. "But when it came out, it came out really well and landed pretty much perfect and ran down there. I was just really making sure I was going to hole the putt, because it was probably the best up-and-down I've had all year."

It kept him at five under par and two clear of the field but there was to be a sting in the tail.

Having birdied the 12th from five feet and two putted for another birdie from long range at the par-five 17th, he then birdied three in a row from the first to surge clear.

After that great par-save at the fifth, he was understandably frustrated to bogey the seventh after taking four to get down from 40 yards after hitting a 368 yard drive.

He went through the green into a bunker with his hack out of the deep stuff there but at the par-three eighth, which measures a ridiculous 278 yards, he found the right greenside trap and lipped out from six feet.

“Yeah, I'm a little frustrated coming off the course, because I feel like it should have been better than what I finished," McIlroy said after finishing the day tied for the lead with Gary Woodland and Jordan Spieth.

"A sloppy bogey or two out there. I felt like I hit a good drive off of 7, and I got into a bit of a tricky spot and made bogey there. And then to make a bogey straight after that, I was a bit frustrated with it. 

"But, you can see by the scores, it's pretty tricky out there and it's -- low scores aren't really that too easy to come by. So a 67 is a really good start, even though it could have been a bit better."

Play was suspended late in the day which left nine players including Graeme McDowell with some holes to complete early today.

McDowell was three over for the day with one to play in an event where he must finish in the Top-5 to progress to the Tour Championship.

Having taken last week off for the birth of his daughter, he opened with a birdie at the 10th but bogeyed the 13th after bunkering his approach and turned in level par before frittering away shots on the front nine.

Bogeys at the first (water off the tee) and second (bad drive) were followed by a birdie from 37 feet at the fourth. But he then bogeyed the fifth (fairway bunker) and the long par-three eighth (bunkered) before play was suspended as he prepared to his a 48 foot birdie putt on his final green. 

McIlroy is hoping to win this week and put himself in position to win the FedEx Cup in Atlanta. But he's also looking forward to seeing the Denver Broncos play the Indianapolis Colts on Monday. 

He met Broncos quarterback Peyton Manning earlier in the week and was given tickets by the former Colts star for the big season-opening game.

"It was cool," McIlroy said. "I met him in the locker room on Tuesday afternoon, and he sort of offered us some tickets for the football game on Sunday night. So, that was really nice of him. 

"To be in this position and to be able to meet other sports people and people that are at the top of their game and profession, it's always a cool thing to do."

Declaring himself an NFL fan, McIlroy added: "What do I enjoy I about it? I mean I'm a huge rugby fan. So, there's obviously similarities with that. 

"Even though you guys play with pads on, which is, you know, I don't understand that. No, it's a great game. It's really, once you start to understand it, and I started to understand it more over the past couple of years, you really get into it and it's such a -- I think the great thing about football is how short the season is. 

"So it's always in demand. People want it. Once the Super Bowl finishes, they can't wait for football season to start up again. I think that's the great thing about it."