Collin Morikawa went on a front-nine birdie spree Saturday to open a two-shot lead at 15-under par after three rounds of the World Golf Championships -- Workday Championship at The Concession in Bradenton, Fla.

Morikawa, the 2020 PGA Championship winner, had six birdies over his first nine holes, including a career-best five consecutive starting at No. 5, and shot a 5-under-par 67 in the third round.

The second of those five consecutive birdies came at the par-3 sixth hole, moving Morikawa into sole possession of the lead at 12-under. It came as Australia's Cameron Smith fell from the top spot after a triple-bogey 7 at No. 5, when he found the water twice.

Billy Horschel and Brooks Koepka were tied for second place at 13-under. Horschel shot a 3-under 69 on Saturday thanks to a birdie at No. 16 and an eagle at the par-5 17th hole.

Koepka shot a 2-under 70 despite working his way through a sore neck and shoulder. He had a one-shot lead at the start of the third round.

Horschel navigated a three-shot swing at No. 17, when he delivered his eagle, while Morikawa had a bogey 6. While Morikawa dropped to 15-under, Horschel moved from 11-under to 13-under and into a tie for second place.

Over a 10-hole stretch from the par-5 third hole until the par-4 12th, Morikawa produced eight birdies, reaching 17-under par and pushing his lead to six shots at one point until a three-putt bogey 6 at No. 13. He had three bogeys during the round, two of which came over his final six holes.

The 24-year old was coming off a second round Friday when he matched a career-best with nine birdies overall.

Webb Simpson was alone in fourth place at 12 under after shooting a 3-under 69. Northern Ireland's Rory McIlroy and defending champion Patrick Reed were tied for fifth place at 11-under

Smith stumbled to a 5-over 77 after hitting a ball into the water four times in the round and had a three-day total of 5-under, putting him in a tie for 20th place.

Simpson and England's Matthew Fitzpatrick were the leaders after Thursday's opening round, with Fitzpatrick shooting a 1-under 71 in the third round to put him in a four-way tie for seventh place at 10 under.

Max Homa, who won last week in the Los Angeles area at the Genesis Invitational, had a 5-under 67, his best round of the tournament, and is alone in 19th place at 6 under.

The tournament has been held at Club de Golf Chapultepec at Mexico City since 2017, but was moved to Florida this year because of COVID-19 concerns.