American Brian Harman remained firmly on course to claim his first major title on a rain-soaked final day of the 151st Open Championship at Royal Liverpool.

Harman took a five-shot lead into the closing 18 holes and maintained that advantage at the turn after recovering superbly from a shaky start.

Only two players in championship history have squandered a five-shot lead after 54 holes, Macdonald Smith in the last Open staged at Prestwick in 1925 and Jean van de Velde at Carnoustie in 1999.

Harman’s lead quickly became six when playing partner Cameron Young bogeyed the first, but Harman dropped a shot himself at the next before Masters champion Jon Rahm closed the gap with a birdie on the par-five fifth.

Rahm’s drive was pulled towards a collection of gorse bushes but somehow avoided all of them and left the world number three with a good lie and clear shot, from where he came up just short of the green and two-putted.

Harman’s tee shot on the fifth then followed the same line as Rahm, only to plunge into a bush and force him to take a penalty drop, leading to a second bogey and cutting his lead to three.

That was just Harman’s fifth bogey of the week and for the third time he bounced back immediately with a birdie, holing from 15 feet on the sixth to edge further clear.

And when he also birdie the next following another quality iron shot, the lead was back to five.

Rahm’s bogey on the ninth briefly gave Harman a six-shot cushion, but Austria’s Sepp Straka almost immediately birdied the 11th to get back within five.

Rory McIlroy, who began the day nine behind, made the ideal start with a hat-trick of birdies from the third and recovered from a bogey on the 10th with a birdie on the 14th. But at six behind, holes were running out for the 2014 winner.