Rory McIlroy three off lead in Pebble Beach Pro-Am

Rory McIlroy marked his debut in the AT&T Pebble Beach National Pro-Am with a four-under effort at Spyglass Hills. Picture: Getty Images

The 28-year-old carded an opening round of four-under 68 to leave him chasing current leaders Kevin Streelman and Beau Hossler.

McIlroy had shot five birdies and one bogey to leave him four-under after 15 holes of the Spyglass Hill course, before a wayward drive gave him another bogey on the 16th.

But the four-time major winner rallied to make a birdie on the 18th and remain among the chasing pack.

Playing partner Phil Mickelson is also in that group after he stormed home in 31 to salvage a 69.

American Streelman and compatriot Hossler, a PGA Tour rookie, shared the top spot after both finishing on seven-under 65 on different golf courses.

Streelman shot seven birdies - including one on the final par-4 18th hole - at Spyglass Hill, while Hossler carded the same, with a spectacular 54-foot putt for birdie on the par-4 16th hole at Pebble Beach.

Dustin Johnson carded a five-under 67 opening round as he bids to hold on to his position as world No 1, with Spaniard Jon Rahm, the man who can topple him if he wins on Sunday, also getting off to a good start with a four-under 67 at Monterey Peninsula.

Returning to Pebble Beach, where he won the US Open, Graeme McDowell finished at one-under 71 after double-bogeying the 17th hole.

It was a disappointing day for defending champion Jordan Spieth, who had to settle for a round of 72 on the Monterey Peninsula course, making one birdie, one bogey and 16 pars.

Russell Knox opened with a one-under 71 at Spyglass Hills, where the Scot made his score with three birdies to finish the front nine.