(AFP) - James Hahn fired his second bogey-free 64 of the week on Saturday (May 20) while Australia's Jason Day charged into contention entering the final round of the US PGA Byron Nelson tournament.

World No. 3 Day blasted a seven-under 63 in the third round at the TPC Las Colinas course just outside Dallas, but was two strokes off the pace as Hahn grabbed the lead on 12-under 198.

"I played well out there. Overall it was a good day," said Hahn, the 18-hole co-leader.

Fellow American Billy Horschel was second on 199 after a 66 that included birdies on his last three holes.

Day had eight birdies to move into a share of third with second-round leader Jason Kokrak, who shot 72. American Cameron Tringale was fifth at 201 after a 67.

Reigning Masters champion Sergio Garcia of Spain fired a 64 to finish on 202 and share sixth with former Byron Nelson champion Jason Dufner (65) and Bud Cauley (68).

Americans Scott Brown (65), Scott Piercy (66), Grayson Murray (68), Chad Campbell (68) and South Korea's An Byeong Hun (69) were on 203.

World No. 1 Dustin Johnson shared 19th after carding a one-over 71 on Saturday, snapping a streak of 14 consecutive par-or-better rounds at the Byron Nelson for Johnson, who is seven shots behind Hahn.

"Mentally and physically I'm fine," Johnson said.

"I'm not as sharp as I was, obviously, before the Masters and it's going to take a little time to get back in that kind of rhythm but I'm seeing good signs."