Jaini, who was tied ninth overnight, was the best placed Indian but eight shots behind Poom Saksansin (68) of Thailand, who stayed in lead for the third day running at the Santiburi Country Club on Koh Samui.
Rahil Gangjee closed with an eagle for a 68, while Jyoti Randhawa had three birdies in last four holes for his 68. At two-under 211, Gangjee is tied 13th and Randhawa at one-under 212 is tied 15th.
Shankar Das, in top-10 after two days, had a sharp fall with 76 and his now tied 36th, while Digvijay (71) was tied 39th. Rashid Khan, whose card included a triple bogey in his 73 is also tied 39th but Chiragh Kumar (76) slipped to tied 65th at eight-over.
Jaini, who lost the 2011 Panasonic Open play-off to Lahiri, had a roller coaster of a round. He had an identical four birdies, one bogey and one double bogey on either side of the course.
EurAsia Cup star Siddikur fired a stunning 64 with seven birdies as he moved into contention for a third Asian Tour victory while two-time Order of Merit champion Thaworn Wiratchant (67) is equal third with countryman Donlaphatchai Niyomchon (71) and Korea's Baek Seuk-hun (71), five off the pace on 206.