Kolkata: Pacer Abhimanyu Mithun bagged his third five-wicket haul of the Ranji Trophy campaign as Vidarbha collapsed for a paltry 185 before Karnataka were reduced to 36/3 at the end of the first day's play where 13-wickets fell in the semi-final at the Eden Gardens here on Sunday.

Karun Nair (6 batting) and CM Gautam (9 batting) were at the crease at stumps with Karnataka trailing by 149 runs. Play was called off 12 overs before the scheduled time due to bad light.

Promising pacer Rajneesh Gurbani (2/9) and India speedster Umesh Yadav (1/22) raised hopes of a comeback by shaving off the Karnataka top-order after Mithun returned figures of 5/45 with all his scalps coming in the second session.

Aditya Sarwate (47) top-scored for Vidarbha, while veteran batsman Wasim Jaffer contributed 39 runs.

Gurbani accounted for the wickets of R. Samarth (6), and Nishal D (0) with beautiful deliveries while Umesh got Mayank Agarwal (15 off 19; 3x4) leg before wicket bowling a probing line.

Umesh -- drafted into the team at the last moment after the Indian team management decided to let him play -- did not look like he was bowling in full tilt keeping the upcoming South Africa tour in mind.

Vidarbha inexplicably chose to bat first after winning the toss despite having Umesh in their ranks.

Karnataka boast of a strong bowling line up too having the likes of skipper R. Vinay Kumar, Mithun, Sreenath Aravind, Shreyas Gopal and Krishnappa Gowtham.

The sight of skipper Faiz Fazal and Sanjay Ramaswamy coming out to open the batting was hard to fathom and their gamble did not bear fruit as Mithun ripped through their middle order bowling some wonderful lengths and always keeping the batsmen on tenterhooks.

While he did not get any wicket in the morning session, with his spell reading 5-3-18-0, the pacer made the most of the movement off the deck to send Ganesh Satish (30 off 56; 6x4), and Apoorv Wankhade (1) packing in the same over. Satish was dropped on 14 by Arvind.

The 28-year-old Mithun, who last played for India in 2011, then grabbed three wickets in four balls in his third spell taking the wickets of Akshay Wakhare (18 off 44; 2x4), Gurbani (0) and Umesh (0), missing out on a hat-trick by a whisker.

In the beginning, skipper Vinay (2/36) swung the ball both ways to trouble the batsmen, getting the wicket of Fazal (12 off 35; 2x4) early.

Stuart Binny (1/48) then sent Ramaswamy back, trapping him plumb in front.

Jaffer looked good for his 39 but Aravind took his wicket with Akshay Wadkar falling to Vinay Kumar some overs later and then Mithun doing the rest to send his rivals packing.

The match started half an hour late as Vidarbha players reached the stadium late due to the traffic snarl because of the 25K Kolkata marathon.

Brief scores: Vidarbha 1st innings: 185 all out (Aditya Sarwate 47, Wasim Jaffer 39; Abhimanyu Mithun 5/45, R. Vinay Kumar 2/36) vs Karnataka 1st innings: 36/3 (CM Gautam 9 batting; Rajneesh Gurbani 2/9) on Day 1.