SPRINGFIELD , New Jersey (AFP) - Unheralded Robert Streb matched the record-low round in Major golf history on Friday with an astonishing seven-under par 63 to seize a share of the lead after the second round of the PGA Championship.

Top-ranked defending champion Jason Day's amazing run of seven birdies in eight holes to grab a share of third was overshadowed by a 29-year-old American on a rain-soaked Baltusrol layout soggy enough to surrender low scores in a wild afternoon of shot making.

Back-nine starter Streb made a lone bogey and eight birdies, the last of them on a curling 21-foot putt at the par-three ninth to make history and match compatriot Jimmy Walker for the 36-hole lead at nine-under 131.

"I was pretty excited about it," Streb said. "I was waiting on it to break, waiting on it to break and it finally turned there at the end. "It was a great round. Happy to be part of that 63 club."

His 63 was the 30th shot at a major but he was the 28th player to achieve the feat, Fiji's Vijay Singh and Australian Greg Norman having done it twice.

Streb, whose lone US PGA victory came in the 2014 McGladrey Classic, has gone 27 US PGA events without a top-10 showing since placing 10th at the 2015 PGA Championship, although he was fourth at this year's European Tour Nedbank Challenge in South Africa.

Streb missed the cut in all three prior Majors this year but played the round of his life to put himself in contention for a Major title.

Australia's Day fired a 65 to stand two strokes adrift on 133 along with Argentine rookie Emiliano Grillo, who shot 67.

Fourth-ranked Rory McIlroy fired a 69 but could not overcome a bogey-less first-round 74 and the four-time Major champion missed the cut on 142 by a stroke.