South Africa's Thriston Lawrence one shot back at US Open

The four-time DP World Tour champion carded six birdies in his 67, one ahead of Si Woo Kim, two-time former champion Brooks Koepka and Im in joint-third. The Mbombela native sits alone in second place.

Meanwhile, Spaun made an impressive start, holing his chip from a tricky spot in the rough at the tenth for an opening birdie before picking up his second shot of the day from close range on the 12th.

After sending his tee-shot to six feet at the par-three 16th to set up another birdie, Spaun holed a ten-footer on the next before parring the 18th to turn in 31 - the lowest first nine in a US Open at Oakmont.

And he made some wonderful par saves on his way in to keep his card clean.

Spaun was thrilled with his start to the week, saying: "I kind of came out here with no prior history at Oakmont, not really knowing what to expect even US Open-wise. This is only my second one.

"I don't know if that freed me up in any aspect, but I just tried to kind of take what the course gave me.

"I hit a lot of good shots and tried to capitalise on any birdie opportunities, which aren't very many out here.

"But I scrambled really well too, which is a huge component to playing well at a US Open, let alone shooting a bogey-free round. I'm just overly pleased with how I started the tournament.

"It definitely makes me feel good, makes me feel confident that I'm leading the tournament. But there's plenty more golf left. This course is only going to get tougher."

Ten players were under par after 18 holes, with Jon Rahm, Thomas Detry, Rasmus Neergaard-Petersen, Ben Griffin and James Nicholas in a tie for sixth on one under.

Defending US Open champion Bryson DeChambeau carded a 3-over 73, tied with world number one Scottie Scheffler, while Masters champion Rory McIlroy managed to post 74.

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