Chris Rogers' double hundred led Middlesex to a target of 472 and a seven-wicket win over Yorkshire on the final day at Lord's.
The Australian hit 241 not out off 290 balls as Middlesex pulled off the third highest run chase in County Championship history.
Starting the final day on 230-1, Middlesex lost Dawid Malan (35) early on but Rogers put on 70 with Eoin Morgan (27) and then an unbroken fourth-wicket partnership of 145 with Neil Dexter (72no) to finish the job in the afternoon session.
Rogers' effort featured 37 fours and is the third highest score made in the fourth innings of a championship match. Middlesex picked up 19 points for their second victory of the season and sit three points off the Division One lead.
Somerset needed just 75 minutes of the final day against leaders Sussex to record a first win of the season with an innings to spare.
Starting the day 68 runs short of making their visitors bat again, Sussex, who resumed on 156-6, saw their hopes of taking the game into any sort of a contest ended when Ed Joyce chopped on for 93.
Marcus Trescothick's decision to make a bowling change 45 minutes in paid off with Lewis Gregory, the game's stand-out bowler, coming on and removing Joyce, who tried a nudge to third man but ended up diverting the ball onto his stumps.
The Ireland international represented Sussex's best chance of salvation and, after he fell just short of a third century of the season, Somerset quickly wrapped up the tail and Sussex's innings for 219 for victory by an innings and 11 runs.
Somerset took 22 points with Sussex, beaten for the first time this season, just three.
Elsewhere, James Anderson completed a 10-wicket match as Lancashire sealed a 60-run win over Northamptonshire in their first match without Peter Moores at the helm.
Moores has already started work as England head coach and will be thankful to have Anderson at his services in that role, as the seamer claimed the first two wickets on the final morning at Wantage Road to tee up victory and finish with combined figures 10-89.
Northamptonshire resumed on the fourth morning 145-5 with 95 still to get but instead mustered only 34 as the visitors finished the job in just 15 overs.
Northants retained a theoretical chance as long as Middlebrook remained but when he drilled skipper Glen Chapple to the waiting Ashwell Prince for 87, the result was all but settled.
Off the field, Lancashire announced the appointment of former club captain Mark Chilton to the coaching staff.