Chasing 149 for a win in a low-scoring encounter at the Railways Recreation Club Ground, Rajasthan were reduced to 81 for seven and then 139 for nine but Bhatia held his nerve in a tense finish to hand Assam their second loss in two days.
Bhatia mixed the right dose of caution and aggression in his 82-ball stay, which was laced with 6 fours and a six.
Krishna Das, Arup Das, Pritam Das and Pallav Kumar Das picked up two wicket each.
Assam 148 all out in 44.4 overs (Pallav Kumar Das 37, Amit Sinha 27; Rajat Bhatia 5-17)
Rajasthan 149/9 in 49.3 overs (Rajat Bhatia 68 not out, AR Gupta 27; Krishna Das 2-17)
Points: Rajasthan 4, Assam 0.