Smith carded an eagle and six birdies on his way to a superb eight-under 64 on the Old Course, seeing him move to 13 under 131 and break the record for the lowest 36-hole total posted in a major.

The world No 6 holed from nearly 50 feet at the first to begin a run of three consecutive birdies and added back-to-back gains from the sixth to reach the turn in 31, with the Australian starting his back nine with a birdie and rolling in a long-range eagle at the par-five 14th.

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The 28-year-old required one birdie in his last four holes to equal the lowest major round at St Andrews and needed to play the closing stretch in two under to match Branden Grace's record 62, only to par his way home and head into the weekend two clear of first-round leader Cameron Young.

Young followed up his opening-round 64 by mixing five birdies with two bogeys in a three-under 69, while McIlroy maintained his push for a first major title since 2014 and third victory of the season by posting a second-round 68.

McIlroy made birdies at the fifth and seventh before cancelling out a long-range three-putt bogey at the eighth by starting his back nine with three consecutive birdies, only to three-putt the par-five 14th for par and three-putt the next to slip back to nine under.

The four-time major winner birdied his penultimate hole to sit in tied-third alongside Hovland, who made a hole-out eagle at the par-four 15th and birdied the last to sign for a six-under 66.

Dustin Johnson made a bogey-free 67 to get within four of the lead and world No 1 Scottie Scheffler is five off the pace alongside Tyrrell Hatton, while US Open champion Matt Fitzpatrick charged back into contention with a six-under 66.

Three-time major champion Jordan Spieth and former world No 1 Jon Rahm are in the group on four under that includes 2019 winner Shane Lowry, as defending champion Collin Morikawa joined Tiger Woods in missing the cut.

Rounds of 78 and 75 left Woods failing to make the weekend in The Open for just the fourth time in his career, with the 46-year-old recording just one birdie in a round where he once again struggled on the greens.

Woods cancelled out a birdie at the second with a bogey at the next and made a three-putt par at the fifth after leaving his initial eagle try five feet from the pin, with the three-time Champion Golfer of the Year bogeying the seventh and then ending a run of pars with a double-bogey at the 16th.

Huge galleries lined the 18th fairway to pay tribute to Woods, who looked emotional as he received a standing ovation from the Scottish crowd, with the world No 994 admitting post-round that he may have played his last major at St Andrews.

"I'm not retiring from the game," Woods said. "But I don't know if I will be physically able to play back here again when it comes back around. I'll be able to play future Opens, yes, but eight years' time, I doubt if I'll be competitive at this level."

Watch The 150th Open throughout the weekend live on Sky Sports' dedicated channel - Sky Sports The Open. Live coverage continues on Saturday from 9am, with Live at The Range, Featured Holes and Featured Groups will be available via the red button on Sky Sports The Open, along with the Sky Sports website and app.