Surrey completed a commanding nine-wicket victory in the final session of their match with Glamorgan to keep the pressure on Division Two pacesetters Worcestershire and Hampshire.
The visitors collected 23 points from their trip to Colwyn Bay, with a third win in four matches and a fourth of the season turning the heat up on the Division Two leaders.
Four wickets for Matthew Dunn and a two-over burst from part-time seamer Arun Harinath, who claimed two key wickets in short order, helped Surrey bowl Glamorgan out for 398 on the final day.
Chris Cooke made an unbeaten 83 to at least make sure that Surrey had to bat again, but needing just 42 to win from 25 overs was never likely to cause any problems.
They did lose opener Rory Burns in the first over, but there were no further scares as Surrey coasted to victory to reach their target with 12.1 overs left to spare.
Unbeaten leaders Worcestershire are not in action, but Hampshire are facing Gloucestershire at the Ageas Bowl, where they trail by 149 runs with the visitors still having five first innings wickets remaining.
Will Gidman's first century of the season underlined his growing importance to the Gloucestershire team, the all-rounder making an unbeaten 109 when coming in at six to help his side to 446-5 by the close.
Gidman featured in a stand of 161 with Ian Cockbain for the fifth wicket, with the 29-year-old adding more than 500 County Championship runs to the 35 wickets he has taken with his medium pace.
A frustrated Hampshire will need quick wickets on the final day while Gloucestershire could yet put pressure on their hosts when they get to bat a second time around.
Josh Cobb scored his first century for two years and Rob Taylor hit a career best 98 as bottom side Leicestershire staged a spirited fightback on the third day of their game against Kent at Grace Road.
The pair shared a sixth-wicket stand of 175 runs to help Leicestershire reach 388 in their second innings and set Kent a victory target of 304.
By the close the visitors had reached 66-1 off 17 overs, leaving them needing another 238 to win.
Rob Key was the man out - trapped lbw by Ben Raine for 16 - but Leicestershire did not help their cause with some erratic bowling which allowed Kent to hit 13 boundaries.
Meanwhile, Nick Browne wrote his name in the Essex record books but Derbyshire hold the initiative after another absorbing day at Chesterfield.
The 23-year-old celebrated his maiden first-class century and became only the 10th Essex player to carry his bat when he was left unbeaten on 132 as his side were bowled out for 277.
Browne occupied the crease for a minute short of seven hours but a burst of 4-14 in 45 balls from former Essex paceman Tony Palladino restricted the visitors to a slender lead of two.
Derbyshire skipper Wayne Madsen made his second 50 of the game and Ben Slater and Shivnarine Chanderpaul also made half-centuries as Derbyshire ended day three on 237-5 to lead by 235.