Essex, Northamptonshire and Kent also moved into strong positions in the lower tiers.
A maiden century for Liam Paterson-White and four wickets from Luke Fletcher left Nottinghamshire in pole position to claim the first Division One victory since the resumption of the LV= Insurance County Championship.
Paterson-White made 101 from number eight on day two against Somerset, cashing in with 18 boundaries to turn Nottinghamshire’s overnight score of 282 for six into a formidable 448 all out at Taunton as Fletcher chipped in 51.
The hosts then crumbled to 87 for seven under the scoreboard pressure, Fletcher running amok with four for 21.
At the Ageas Bowl, Yorkshire were also busy moving themselves into a position of strength against Hampshire. The White Rose lost their last four wickets for 47 to set a first-innings mark of 243, before a fine bowling performance left them with an 80-run lead.
Seamers Ben Coad and Jordan Thompson took three apiece, with Dom Bess following his earlier half-century with two of his own, as Hampshire folded for 163. Tykes opener Adam Lyth fell before the close but at 34 for one they remain on top.
Things were more evenly poised at Emirates Old Trafford in the remaining top-flight game, Lancashire responding to Warwickshire’s 371 all out with a score of 100 for one by stumps.
The home attack hit back after a tough first day that saw Chris Benjamin and Sam Hain hit hundreds, with England duo Saqib Mahmood (four for 77) and Matt Parkinson (three for 96) among the wickets. George Balderson was the dismissed for a duck in reply before Luke Wells and Josh Bohannon (59no) rebalanced the scales.
In Division Two, Essex were making light work of Glamorgan at Cardiff. The hosts slumped to 71 for six in their second innings and will begin day three 115 runs behind with captain Chris Cooke fighting a lone hand on 39no.
Nick Browne had earlier converted his half-century into 102, but Dan Lawrence had to settle for 34 before linking up with the Test squad.
Northamptonshire pair Ben Sanderson and Luke Procter wrecked Gloucestershire’s batting order, splitting the wickets as the home side limped to 90 for six at Bristol.
The seamers took three for 22 and three for 13 respectively, making a strong defence of their side’s 327 all out. Skipper Adam Rossington had earlier fallen six short of a century, becoming one of four victims for Tom Price.
In the third tier, Leicestershire had a mountain to climb against Kent at Grace Road. The home side had their visitors 210 for nine at the close, but remained 333 behind in a match where the highest score in three innings has been 232.
Zak Crawley, Joe Denly and Sam Billings were all over-shadowed on the day by 45-year-old Darren Stevens, who was unbeaten on 55 at the close. Callum Parkinson bagged a second-innings five-for to take his match tally to nine.
Middlesex appear to be in control at Lord’s, reducing Derbyshire to 201 for nine having posted 282. Veteran Tim Murtagh linked with up-and-comer Ethan Bamber as both men took four wickets, while batsman Leus du Ploy battled back with 90.
At New Road, Worcestershire were 186 for seven as they attempted to match Sussex’s 264, Jack Haynes’ 47 the pick of the innings.