Alex Hales' 96 helped Nottinghamshire eat into Middlesex's mammoth 505 first-innings score at Trent Bridge, where the hosts finished day two of their LV= County Championship Division One match on 258 for four.
A record-breaking stand on Saturday between centurions Eoin Morgan and Chris Rogers had given the hosts a commanding platform.
However, Hales also enjoyed a good spell at the crease, while Michael Lumb contributed 47 and Samit Patel was still unbeaten on 75 at stumps.
Resuming on 174 overnight, Morgan saw Paul Stirling (31) and then Toby Roland-Jones (18) both depart before his long innings was finally brought to an end.
Luke Fletcher made the breakthrough as he had Morgan caught behind for 191, with Middlesex at 481 for eight.
The tail was then mopped up, Tim Murtagh finishing 28 not out in Middlesex's imposing 505.
There was a delayed start to the afternoon session because of rain, but Notts went on to make good use of the rest of the day.
Mattheus Wessels (26 not out) offered support to Patel after Hayles had been trapped leg-before by Murtagh just shy of his century.
At Chester-le-Street, Kyle Hogg claimed five wickets as Lancashire made positive early moves on the first day against Durham, who rallied to reach 310 at stumps.
Hogg - with just 62 runs coming off his 23 overs with nine maidens - dismissed captain Paul Collingwood for just one, while Thomas Smith also claimed two wickets.
However, Durham, having been 184 for eight, mounted a late recovery to finish the day without further loss after fine unbeaten half-centuries from number 10 Paul Coughlin (71) and wicketkeeper Phil Mustard (61).
Opener Mark Stoneman had offered some earlier resistance, third man out for 51.
An unbeaten century from Robert Newton helped bottom club Northamptonshire reach 297 for eight against Warwickshire.
The hosts were earlier 66 for three after they lost two wickets in the 18th over when first James Middlebrook (33) was caught behind off Rikki Clarke, who then bowled Robert Keogh for a duck.
Matthew Spriegel (16) was soon lbw to Chris Wright and then in the next over, Richard Levi's promising knock was ended on 43 when he was caught behind off Christopher Woakes for 43 and Northants were suddenly five down for 119.
However, Newton, supported by 45 from Andrew Hall, helped steady the innings and stayed unbeaten at the crease for more than three-and-a-half hours to end the day at 108.
In Division Two, Derbyshire's struggles continued as they were skittled out for just 153 inside 50 overs by Surrey, with 19-year-old Thomas Curran claiming five for 51.
Jade Dernbach also took three for 41, having removed both Marcus North (44) and then Alex Hughes, for a duck, in the same over before returning to quickly send Scott Elstone back to the pavilion.
In a rain-hit reply, after Rory Burns was lbw to Mark Footitt in the second ball, Surrey went on to reach 44 for one by stumps, Hashim Amla (25no) and Zafar Ansari (15no)
Second-placed Hampshire made a positive start against Essex at Southampton, scoring 286 before taking two late wickets.
Having been put in to bat, the home side scored solidly, with Adam Wheater (42) and James Vince (41).
Reece Topley and England all-rounder Ravi Bopara finished with three wickets each.
However, Tom Westley (one) and then Bopara (one) were both out cheaply as Hampshire enjoyed some late success. Essex were 55 for two at stumps. Captain wicketkeeper James Foster was unbeaten on 26.
A half-century from Kent captain Robert Key (63), the former England batsman, helped his side reach 236 for eight at Glamorgan.
Veteran Australian Michael Hogan returned three wickets for 47 runs from his 21 overs, with six maidens.
At Leicester, Alexei Kervezee made 102 as Worcestershire reached 237 all out.
In reply, Leicestershire were 58 for two.