After winning a good toss on a green top, Unadkat along with fellow left-arm pacer Sakariya set the tone in the morning session, dismissing their top-four batters inside 17 runs.
Bengal's dream of winning a Ranji Trophy after more than three decades suffered a setback as left-arm Saurashtra pace duo of Jaydev Unadkat and Chetan Sakariya rattled the home team's top-order to bundle them out for a paltry 174 on the opening day of the summit clash in Kolkata on Thursday. (More Cricket News)
It would have been more embarrassing for Bengal but spin all-rounder Shahbaz Ahmed (69) and wicketkeeper Abhishek Porel (50) saved the hosts from the blushes with gritty half-centuries.
The duo showed the way for the top-order in a 101-run stand for the seventh wicket and batted close to four hours to frustrate Saurashtra.
But they looked in a sense of urgency and took risks as Saurashtra wrapped up Bengal innings' with left-arm spinner Dharmendrasingh Jadeja (2/19) scalping two wickets.
At close on day one, Saurashtra were 81 for 2, trailing Bengal by 93 runs.
In-form opener Harvik Desai (38), who has more than 600 runs this season, was at the crease with night watchman Sakariya (2).
The duo survived some late charge by Bengal pace duo of Akash Deep and Mukesh Kumar to bring the deficit under 100.
With their leading run-getter of the season Aprit Vasavada (826 runs at 75.06) yet to come along with the prolific duo of Sheldon Jackson (529) and Chirag Jani (509), Saurashtra would definitely fancy a first innings lead.
Bengal bowlers looked pedestrian at start but Akash Deep and Mukesh Kumar took some purchase in the fag end of the day to dismiss Jay Gohil (6) and Vishvaraj Jadeja (25) respectively.
Making a comeback after being released from the Test side, Unadkat (3/44) produced a terrific opening spell of 5-2-7-2, while Sakariya (3/33) made the ball talk in initially to reduce Bengal to 17 for 4 inside 31 minutes.
Bengal lost half of their side at the score of 34 for 5 in one hour and 13 minutes with third seamer Chirag Jani (2/33) also making good use of the lively Eden surface.
After winning a good toss on a green top, Unadkat along with fellow left-arm pacer Sakariya set the tone in the morning session, dismissing their top-four batters inside 17 runs.
Surviving the first-hour's play when the ball swings viciously on the Eden strip was always going to be key and Bengal are well-versed with the home conditions.
But it was the visitors who exploited the conditions well, bowling a probing line that teased the batters' off-stump.
The need of the first hour was to show some patience and judge the ball well, but the top-four Bengal batters went on with pre-mediated shots and lasted just 29 balls.
Abhimanyu Easwaran showed a sheer lack of application and fell for a duck becoming Unadkat's victim in the fifth ball of the day.
The spirited start pumped up the Saurashtra camp and Sumanta Gupta, making a debut in the final, could not sustain the pressure, succumbing to a peach of a delivery from Sakariya at the other end to be out for one.
Sakariya was on a roll as he cleaned up Sudip Kumar Gharami's off-stump two balls later.
Skipper Manoj Tiwary became Unadkat's second victim when he poked at a wide delivery to edge one to Vishvaraj Jadeja at gully.
All eyes were on another veteran Anustup Majumdar, who was Bengal's leading run getter this season, to revive the innings.
Majumdar also built a mini partnership with rookie pace bowling all-rounder Akash Ghatak, who replaced Pradipta Pramanik in the playing XI, and was promoted to No 6.
But Majumdar played a freak shot against Saurashtra's third seamer Jani as Bengal lost half of their side at the stroke of drinks in the first session.
From 34 for 5, Shahbaz took charge of the proceedings and counter-attacked the Saurashtra bowlers hitting 11 boundaries.
Luck also was on his side as he got a reprieve on 26, while on 38 a Prerak Mankad delivery looked to hit the stump on replay but Saurashtra did not make use of the DRS.
Brief Scores:
Bengal: 174 all out in 54.1 overs (Shahbaz Ahmed 69, Abhishek Porel 50; Jaydev Unadkat 3/44, Chetan Sakariya 3/33, Chirag Jani 2/33, Dharmendrasinh Jadeja 2/19) vs Saurashtra 81 for 2 in 17 overs. Saurashtra trail by 93 runs.