Troon (United Kingdom) (AFP) - American Billy Horschel leads the British Open at four under par heading into Sunday’s final round after torrential rain and a swirling wind at Royal Troon blew the challenge for the Claret Jug wide open.

Horschel leads by one from a group of six, featuring USPGA Championship winner Xander Schauffele, English duo Justin Rose and Daniel Brown, South Africa’s Thriston Lawrence and Americans Sam Burns and Russell Henley.

World number one Scottie Scheffler is just one shot further back at two under after battling to an even par round of 71.

A total of 12 players are within four shots of the lead for what promises to be a fascinating final round.

Overnight leader Shane Lowry had a day to forget as the 2019 champion crumbled in the sodden conditions to collapse from eight under par after seven holes to one under by the end of his round.

Horschel was one of the big movers in a round that had allowed for lower scoring earlier in the day before the wind and rain picked up.

Starting at two under, Horschel produced a sublime four-under 32 on the front nine thanks to birdies at four, six, seven and nine.

A bogey followed at 11 before another dropped shot at the last.

Brown, ranked 272 in the world, had been set to lead heading into the final round until a double bogey at the last.

But he and Rose remain in the hunt to become the first English winner since Nick Faldo in 1992.

Lowry began the day with a two-shot lead and extended that to three with a birdie at the par-five fourth.

However, the Irishman’s round began to come off the rails with a double bogey at the 130-yard Postage Stamp eighth.

Worse was to come as five bogeys in eight holes on the back nine dropped Lowry back into ninth.

- Schauffele ‘dreams’, Scheffler poised -

Fresh from his maiden major win at the USPGA, Schauffele is eyeing another.

The world number three moved to five under at one stage before bogeys at 11 and 18 knocked him back to three under after a round of 69.

“I’ll let myself dream tonight,” said Schauffele.

Scheffler is also right in the mix to win his third major and win for a seventh time in 15 starts this year.

A birdie at the third got the American off to a fine start but he then played the next 13 holes in two over before picking up a shot at the 17th to remain ominously poised.

“The back nine, I think that was probably the hardest nine holes that I’ll ever play,” said Scheffler.

Lawrence, Burns and Henley made the most of the benign early morning conditions to shoot through the pack to three under.

Lawrence and Burns posted six-under 65s, while Henley made 66 to move into contention before the leaders had to face the worst of the weather.

Two-time major champion Justin Thomas and former Masters winner Adam Scott also impressed to move to level par and remain on the fringes of the battle for the Claret Jug.

But the challenge from the big names on the breakaway LIV circuit failed to materialise.

Jon Rahm slipped back to two over, while Brooks Koepka is back at eight over after a 78.

One of the loudest cheers of the week so far was reserved for Si Woo Kim after he produced the longest hole-in-one in British Open history on the 17th that brought him back to five over for the tournament.

“I was not doing very well, and then I was feeling terrible for my shots the last couple days. Then finally I got the best golf shot I’ve ever had this week,” said the South Korean.