ERIN, WISCONSIN (AFP) - Unheralded American Brian Harman will take a one-shot lead into the final round of the US Open after firing a five-under 67 to nose ahead of a crowded leaderboard on Saturday (June 17).

Harman, who missed the cut both times on his only other US Open appearances in 2012 and 2015, held his nerve to fire six birdies and only one bogey on a day of record-breaking low scoring at Erin Hills Golf Course.

The 30-year-old world No. 50 from Georgia, headed to the clubhouse on 12 under, one ahead of Justin Thomas (63), Brooks Koepka (68) and England's Tommy Fleetwood (68).

Rickie Fowler was two behind Harman on 10 under after a four-under 68 which kept him firmly in contention.

South Korea's Kim Si Woo was one behind Fowler on nine under after also shooting 68, while three players - Patrick Reed (65), Russell Henley (67) and Charley Hoffman (68) were on eight under.

Overnight rain created soft conditions which made for a feast of birdies.

The prime beneficiary was American Thomas, who shot a magnificent nine-under 63, the lowest to-par score for 18 holes in US Open history