Rory McIlroy loses ground on day two of the Pebble Beach Pro-Am as an erratic two-under-par 70 puts him six behind leader Austria's Sepp Straka.

Just hours after Rory McIlroy slam-dunked a hole-in-one on the 15th hole at Spyglass Hill, Shane Lowry made an ace on the 7th hole at Pebble Beach, one of the most famous par-3s in the world.

Rory McIlroy hit just the second hole-in-one of his PGA Tour career on Thursday, a remarkable slam dunk ace on Hole 15 of the Pebble Beach Pro-Am at Spyglass Hill.

Rory McIlroy and Shane Lowry didn’t manage to claim the first round lead in the AT&T Pebble Beach Pro-Am – that honour fell to American Russell Henley – but the two Irishmen stole the highlight reels in each recording holes-in-one in the $20 million PGA Tour signature event, as each used their aces to move into contention.

Rory McIlroy played often in the "offseason" and looked sharp in his first PGA Tour round of the real season, shooting 66 at the AT&T Pebble Beach Pro-Am.

Shane Lowry and Rory McIlroy were in high spirits after both carded hole-in-ones during the opening round of the ATandT Pebble Beach Pro-Am on Thursday

Rory McIlroy and Shane Lowry are both on eight-under par heading into the weekend at the AT&T Pebble Beach Pro-Am after rounds of 70, though they took very contrasting paths to get there.

Rory McIlroy and Shane Lowry two shots off the lead after hitting holes-in-one during first round of Pebble Beach Pro-Am; Justin Rose carded seven-under 65, one shot behind clubhouse leader Russell Henley;

Shane Lowry was quick to get the beers in after he followed Rory McIlroy by sinking a hole-in-one at the Pebble Beach Pro-Am. McIlroy achieved the second ace of his PGA Tour on the par-three 15th

Rory McIlroy marked his PGA Tour season debut with a sensational hole-in-one on his way to a six-under-par 66 in the opening round of the PGA Pebble Beach Pro-Am tournament

Shane Lowry had himself a day at Pebble Beach, sinking an ace and going wild afterward as he sits near the top of the leaderboard.