The 21-year-old, who became the youngest winner of the prestigious Players Championship last month, added a four-under par 68 to his opening 69 and second-round 70 for a nine-under 207 total to stand three behind leader Brian Harman.
Overnight rain once again softened the long, links-style layout and enabled some players to go very low again, which South Korean Kim seemed to feel hurt his chances.
U.S. Ryder Cup standout Patrick Reed fired a seven-under 65 to reach eight-under, and this season’s three-time PGA Tour winner Justin Thomas shot a U.S. Open record nine-under-par 63 to trail Harman by just one stroke.
« Overnight raining and then course was soft, and no wind today, » said Kim. « I think every pin (you) needed to go to the pin. I think it’s much easier today, the last two days.
« I don’t think it’s good for me. Today is too easy, other players may go lower. I’m playing good today, but (I’m) like three behind now. »
With no rain in the immediate forecast and the chance that winds could pick up, Erin Hills may finally show its teeth.
« Just trying to play my golf tomorrow and that’s it. Just aggressive, » said Kim. « Today I was a little nervous and then (felt) pressure. But the back nine is much better, getting better tomorrow, too. »
Hideki Matsuyama, the other serious contender this week to become the first Asian man to win the U.S. Open, failed to take full advantage of the favorable conditions as he registered a 71 to stand six under par, six strokes behind Harman.
The Japanese world number four had vaulted up the leaderboard on Friday with a second-round seven-under 65.
(Editing by Peter Rutherford)