Singapore - Defending champion Jazz Janewattananond took the second round lead at the Singapore Open with a six-under-par 65 Friday but Olympic medallists Justin Rose and Matt Kuchar were snapping at his heels.
All three men's golf medallists from the 2016 Rio Olympics are competing at the tournament in a closely-watched showdown ahead of the Tokyo Games starting in July.
However Thailand's Jazz put in the most impressive second-round performance.
He did not get off to a great start, bogeying the second hole, but quickly found his rhythm with three birdies on holes four, eight and nine.
The 24-year-old fired another four birdies in his back nine for a two-day total of 10-under-par 132 at the Sentosa Golf Club.
"There are still two more days and anything can happen," said Jazz.
"There are a lot of good players here - Kuchar and Rose are still within reach, and I will just stick to my plan and hopefully will take a win for the weekend."
England's Rose, who won gold at Rio, and bronze medallist Kuchar fired 66 and 68 respectively and ended the day in tied fourth place.
But Olympic silver medallist, Sweden's Henrik Stenson, languished further down the field after carding 72.
"There were some difficult holes out there," conceded Kuchar.
But the American added he was "in a good position for the weekend. Today I had a good number of putts go in as well, I think it was a good two days".
Miguel Tabuena of the Philippines scored 65 and was in joint second place with South Korean teenager Kim Joo-hyung, who fired 66.
Ten Olympians are competing at the $1 million SMBC Singapore Open, which runs until Sunday and is jointly sanctioned by the Asian Tour and Japan Golf Tour Organization.
The Rio Games marked golf's return to the Olympics after a 112-year absence.