SOUTHPORT, United Kingdom (AFP) — Sam Burns will have a two-shot lead entering Sunday's final round of the British Open as Rory McIlroy launched a scathing attack on Bryson DeChambeau after his third round on Saturday.

American Burns is one of three players to match the record low score at a major of 62 at Royal Birkdale over the past two days and backed up his historic second round with a 65 to move to 10 under par.

Ryan Fox joined the 62 club with the best round of the day to get to eight under, alongside South Korea's Kim Si-woo.

DeChambeau's two-shot penalty after his second round on Friday for "inadvertently improving" his lie as he addressed his second shot at the fifth hole could still prove crucial.

The American was one under for the day to get to six under for the tournament and would likely have been in Sunday's final group but for the sanction.

DeChambeau appeared to trample down long grass as he addressed his ball for a practice swing.

After an animated discussion with a rules official at the site of the incident, Sky Sports reported DeChambeau had even threatened to withdraw from the tournament late on Friday.

That resulted in a delay to tee times being issued for the third round.

McIlroy's hopes of adding to his six majors look forlorn after a third round 69 left him at two under for the tournament.

But the Northern Irishman was still the focus of attention after he did not hold back on DeChambeau's antics.

"I won't pretend to be up here and defend Bryson. I'm not particularly fond of him. I think a lot of it's performative. I think a lot of it's for attention," the Masters champion said.

"To hold the tournament hostage like that, and to have all of us, players, volunteers, everyone waiting on him to depart, I didn't feel like it was a great look."

Burns is yet to win a major, but finished just one shot behind Wyndham Clark at the US Open last month.

The world number 18 was not even supposed to travel to England's north-west coast with his daughter due in the middle of July.

But baby Belle arrived 11 days early and Burns was given the go-ahead by his wife to compete.

Burns said becoming a dad eases the pressure and puts things into perspective ahead of a potentially career-defining round.

"Tomorrow, all I can do is play my best and see where it puts me. Go out tomorrow and try to execute," he said.

"Ultimately whatever happens tomorrow it doesn't define who I am. That's a very freeing thing to know. I wish my family was here and counting down the minutes to get home and see them again."

Fox and Kim are his closest challengers after the big names on the leaderboard failed to make a mark on moving day.

There had only been five rounds of 62 in major history prior to this tournament, but there are now eight after New Zealander Fox joined Lucas Herbert and Burns.

"I think it's just the good weather conditions. The course is brilliant. It's obviously very firm and fast," said Fox on the reason for the spate of 62s.

"You feel like you can shoot a score in the morning and the greens are perfect, that if you do roll it well, you feel like you hole everything."

American Ryan Gerard and Australia's Herbert are three off the lead at seven under.

Roared on by huge local support, home favourite Tommy Fleetwood made his move to at one point close to within one shot of the lead.

However, he dropped two shots in the final four holes to fall back to five under and give himself a mountain to climb to win his first major in his home town of Southport.

Defending champion Scottie Scheffler was again let down by his putting in a level par 70, which left him down at four under alongside Jon Rahm and former champions Shane Lowry and Xander Schauffele.