Nottinghamshire's opening partnership of Ben Slater and Haseeb Hameed added 172 for the first wicket to mitigate Somerset's lead on the third day at Trent Bridge, after the visitors' tail wagged across the first half of the day.
Migael Pretorius scored a career-best 94 not out from 71 deliveries, while Jack Leach amassed 37 to give their side a first innings total of 470 all out - a lead of 110.
But after Dillon Pennington claimed the final wicket of Jake Ball to give him his first five-wicket haul in green and gold, Hameed's typically stoic 91 complemented Slater's unbeaten contribution of 70 to give Notts a 67-run lead with nine wickets in hand going into the final day .
The Wyverns had resumed proceedings 293/4, but their ascendency appeared compromised when they lost three wickets for six runs.
Tom Abell was the first to depart for 111, struck in front by one that straightened from Calvin Harrison, before Kasey Alrdidge was caught brilliantly by Harrison diving to his right in the slips off Pennington's bowling.
The pacer struck again with his next ball to reduce Somerset to 321/7, finding sharp bounce off the pitch to induce an edge from James Rew for 49.
A short-lived yet industrious cameo from Craig Overton (20 from 13 deliveries) offered extra impetus to the visitors before Pennington trapped him in front for his third wicket of the morning, catalysing the start of Pretorius' onslaught.
The Proteas bowler struck eight fours and six sixes in his innings, for the bulk of which Leach played foil at the other end, the partnership worth 79 by the time the latter perished at the hands of Harrison.
Pretorius enjoyed the bulk of the strike, still, with Ball for company - adding another 35 with contributions solely from the South African before his partner was lbw.
With the best part of 50 overs still to bat, Hameed and Slater picked off Somerset impressively, balancing attack with defense in a stand which put Notts firmly back in the contest.
Slater faced 101 deliveries for his half-century brought up shortly after tea, with his top-order partner needing seven balls more for the feat.
Hameed's demise came with just five overs remaining, bowled by Overton having struck ten fours in his innings, before Olly Stone saw off the remainder of the evening with Slater.
Leading by 67 at the close, the pair will resume Notts' search of a winnable lead at 11am, with all results still possible.