(Updates after leaders reach the turn)
By Mark Lamport-Stokes
KOHLER, Wisconsin, Aug 16 (Reuters) - Australia's Jason Day stayed on course for his first major title as he preserved his overnight two-shot lead midway through Sunday's final round of the PGA Championship.
Boosted by a 50-foot putt at the seventh, Day mixed four birdies with a bogey to reach the turn in three-under 33 on a blustery afternoon of hazy sunshine at Whistling Straits.
That left the Australian at 18 under for the tournament, two ahead of South African Branden Grace and four clear of Masters and U.