A match-winning 102 from Ryan Patel helped Surrey cement their position at the top of LV= Insurance County Championship table by beating Somerset by three wickets at the Kia Oval.
Surrey, needing 237 to win, completed their second victory from the first three games with Patel joined by Ben Foakes in a decisive fourth-wicket partnership of 66.
But Foakes played skilfully for 48 not out after joining Patel at 106 for three, Surrey having just lost both Hashim Amla, for 14, and Ollie Pope, for five, in the first half-hour after lunch.
When Patel finally fell, edging Josh Davey behind after a superb 133-ball innings featuring 14 fours and plenty of judicious attacking intent, Surrey's total had reached 172 and much of the hard work had been done.
Certainly without Patel's aggressive knock, his second championship hundred and a career-best, Surrey's chase would have been far trickier than it already looked on a pitch still giving the bowlers enough reasons for optimism.
It is a sorry seventh successive championship defeat for Somerset, going back to the end of last summer. Surrey take 21 points and Somerset six.
Warwickshire get off the mark
Warwickshire claimed their first victory of their LV= Insurance County Championship title defence by beating Essex by 10 wickets on the final day at Edgbaston.
Essex resumed the last morning on 290 for eight, just 73 ahead and only added another 33 to be all out for 323 and leave the home side a victory target of 107 in more than two sessions.
Both wickets fell to concussion substitute Craig Miles, who ended with four for 85, while Simon Harmer was left stranded on 75.
Openers Alex Davies and Dom Sibley, with 65 and 41 respectively, eased Warwickshire to victory with an unbroken stand of 110 in 37.4 overs.
The emphatic win rounded off a strong start to the season for the Bears after their solid opening-game draw with Surrey.
Essex were left to digest their first defeat of the campaign and also the blow of England batter Dan Lawrence's hamstring injury which is likely to sideline him for several weeks.
Derbyshire wrap up innings victory over Leicestershire
Leicestershire were eventually all out for 250 as Derbyshire secured victory by an innings and 68 runs. Off-spinner Alex Thomson was the pick of the Derbyshire bowlers, taking three for 50 from 39 overs.
Pakistan international Shan Masood's second consecutive double century and a maiden first-class hundred by Mattie McKiernan had given Derbyshire such a big advantage at the halfway stage of this match, they would have seen this as a wasted opportunity had they failed to win.
Louis Kimber picked up six boundaries and passed fifty for the fourth time in only his eighth first-class match and Callum Parkinson battled for more than two hours but these were only a few positives that Leicestershire can take forward from a disappointing four days.
Ed Barnes, whose maiden five-wicket haul at the end of the Derbyshire innings was another, stayed with Kimber for the first hour of the final day, but fell four overs after the second new ball was taken, Suranga Lakmal having him caught behind off an inside edge on to pad.
It is only the second time in 58 years that Derbyshire have beaten their East Midlands rivals by an innings and the first time at Grace Road, as the Uptonsteel County Ground is traditionally known, since 1896.
Indeed, the win over Leicestershire by an innings and 32 runs at Derby in 2011 was Derbyshire's last innings victory over any opponent.
Hampshire thump Kent
Hampshire beat Kent by an innings and 51 runs at Canterbury after dismissing the hosts for 296 in their second innings on day four.
Kyle Abbott took five for 29, cleaning up Kent's tail with three wickets from four balls, while Felix Organ claimed three for 63 as the visitors secured a maximum 24 points, while Kent managed just four.
Ben Compton and Jordan Cox had given Kent hope of a draw after batting through the morning session on day four, by leaving the side on Kent 161 for three. But they were out for 89 and 64 respectively after lunch and that spelled the death knell for the hosts.
Lancashire win again
Lancashire wrapped up a second consecutive victory despite some impressive resistance from Gloucestershire at Emirates Old Trafford.
The visitors resumed on 67 for three still a long way short of Lancashire's first-innings total of 556 for seven but it took until just before 6pm for the home side to seal the win by an innings and 57 runs with just 23 balls remaining.
Northants dig deep to gain draw
Will Young's six-hour vigil for 96 thwarted Yorkshire's hopes of victory as Northamptonshire dug in to secure a draw.
The Northamptonshire opener batted painstakingly to hold their second innings together, narrowly missing out on a debut hundred after he played on to Matthew Revis with 26 overs remaining.
But wicketkeeper Lewis McManus seized the baton with a spirited unbeaten 62 to steer the home side - set a nominal target of 499 - to safety at 318 for seven.