Matthew Fitzpatrick carded the lowest round of the day so far with a 64 to set the clubhouse target as round two of the WGC-FedEx St. Jude Invitational moved towards its conclusion at TPC Southwind.
The Englishman made seven birdies and a single bogey to get to nine under and lead the way from Australian Cameron Smith, who had four holes left to play.
Overnight leader Jon Rahm and Japanese duo Shugo Imahira and Hideki Matsuyama were still out on the course at six under, a shot clear of Swede Alex Noren, English pair Ian Poulter and Justin Rose, World Number One Brooks Koepka and another American in Webb Simpson, who were all in the clubhouse.
Fitzpatrick is a five time European Tour winner and is now right in the mix for a first World Golf Championships title after carding his lowest round in a WGC event.
He made a stunning start with four birdies and most of that was due to some brilliant iron play.
He holed from 26 feet on the second but his approaches to the first and third were both to eight feet, while he put his tee shot on the par three fourth to nine.
The 24-year-old very briefly had a share of the lead when Rahm bogeyed the par five third after nearly finding the water but he made a bogey of his own after finding sand off the tee at the par three eighth.
Rahm then missed the green at the fourth to make it back to back bogeys and another brilliant approach to seven feet from Fitzpatrick at the ninth edged him ahead.
Patrick Cantlay joined him as he put a tee shot to eight feet on the eighth but Fitzpatrick was absolutely dialled in, and a seven footer down the hill at the 12th moved him to eight under.
Smith had holed from 19 feet on the fourth and made a chip for par on the sixth after making a mess of his first effort, before an approach to inside ten feet on the ninth moved him one back.
Noren had found water on the 12th and double bogeyed the 14th after a three putt to sit three over for his round but showed signs of life as he birdied the par five 16th.
Excellent approaches to the first and second got him back to level for the day and when he made the most of the next and put his second to 11 feet at the sixth, he was just two off the lead.
A bogey on the ninth saw him set the target at five under and he was joined at that mark by Cantlay, who sent his tee shot a long way left on the 12th and then three putted.
Fitzpatrick may have been picking up shots with his iron play but he holed from 27 feet on the 16th to get to nine under and lead by two.
Smith would not be left behind, however, and hit a beautiful approach into the 12th to trim the lead back once more.
Rahm found water on the 12th and dropped further back, leaving Imahira as the only player at six under after he sandwiched a bogey on the 15th with gains on the 13th and 18th.
Matsuyama was also making steady progress and he birdied the third to go with a gain on the 11th and a bogey on the 17th to join his countryman three off the lead.
Rahm then made a first birdie of the day from 18 feet on the 13th to get into the group in third.
Rose signed for a 68 with three birdies on his second nine, while Poulter made two birdies and a bogey in his 69.
