The three men's golf medallists from the 2016 Rio Olympics are playing in the tournament and their performances could give clues about their form ahead of the Tokyo Games starting in July.
Bronze medallist Kuchar of the United States has looked the strongest of the trio, and an impressive round Saturday gave him a three-shot lead heading into the event's final day.
The nine-time PGA Tour winner fired four birdies in his front-nine, followed by another five in his inward-nine for a three-day total of 17-under-par 196.
"It was a great day," said the world number 24.
"That was a great way to start, back to back birdies, kind of tied for the lead there, and just kept playing some good golf.'
Rio gold medallist Rose from England, ranked ninth in the world, did not seem to playing at his best but birdies on the 17th and 18th helped him to a 68 to draw within six shots of Kuchar.
"I wasn't very happy with how I played today," he admitted.
"I knew I needed to have a stronger finish, I knew I went a bit flat in the back nine until the end."
There was disappointment for Olympic silver winner Henrik Stenson, however, who only managed a three-over-par 74 and slipped down the leaderboard to joint 46th.
Meanwhile defending champion Jazz Janewattananond, who had been leading before the third rond, slipped behind Kuchar but still fired an impressive 67 to share second place with Miguel Tabuena of the Philippines.
Thailand's Jazz had a slow start but made up for it with four birdies on the back nine.
Ten Olympians are competing at the US$1mil SMBC Singapore Open, which is jointly sanctioned by the Asian Tour and Japan Golf Tour Organisation.
The Rio Games marked golf's return to the Olympics after a 112-year absence. - AFP
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