Pavit Tangkamolprasert fired a second-round 65 to share the lead at the 15th Singha Masters in Chiang Rai yesterday.
Making seven birdies in a bogey-free round at the par-72 Santiburi Country Club, Pavit was on 133 along with Poosit Supupramai (67).
Poosit had a poor start with a first-hole bogey but fought back with six birdies.
Veteran Thaworn Wiratchant, the 2007 champion, made a 68 with an eagle, four birdies and two bogeys to stay one shot behind the leaders.
One of three overnight co-leaders, Chapchai Nirat made five birdies against a double bogey for a 69. He stayed joint fourth on 135 with Kwanchai Tannin (66).
Evergreen Boonchu Ruangkit fired six birdies in a bogey-free round for a 66 for a total of 137.
Four-time winner Prayad Marksaeng bounced back from his opening 75 to register a second-round 66 for 141.
On the women's side, Rungthiwa Pangjan posted a second-round 72 for a one-shot lead on 142.