|Specsavers County Championship Division One, Cloudfm County Ground (day three):|
|Surrey 174 & 181: Clark 33; Harmer 7-58|
|Essex 395: Lawrence 147, ten Doeschate 103, Harmer 50*; Clarke 3-52|
|Essex (23 pts) beat Surrey (3 pts) by and innings and 40 runs|
Spinner Simon Harmer bowled Essex back to the top of the Division One table by taking 7-58 as they beat Surrey by an innings and 40 runs at Chelmsford.
The win means Essex will go into next week's title-deciding away game against Somerset with a 12-point advantage.
Skipper Ryan ten Doeschate made 103 and Harmer contributed an unbeaten 50 to Essex's first-innings total of 395.
Surrey were then reduced to 80-5 by Harmer, and were eventually all out for 181 when he dismissed Morne Morkel.
Essex are still in with a chance of a double this season and will now go to Edgbaston for Saturday's T20 Blast Finals Day.
They added 93 to their overnight 302-6, with Ten Doeschate reaching his century off 120 balls with a square cut off Amar Virdi before edging the spinner to slip.
Virdi claimed 3-116 and finished off the innings when Aaron Beard was caught at mid-on at the start of the 110th over, with Essex five runs short of maximum batting points.
Mark Stoneman helped himself to three early boundaries as Surrey began their innings, but Harmer then had him lbw to start the away side's collapse.
Ollie Pope was caught at mid-wicket for 30, hammering his bat into his pad in annoyance at the stroke, and having caught Rikki Clarke at slip off Jamie Porter Harmer returned to the attack to have Ben Foakes leg-before for 15.
Jordan Clark and Morkel held Essex up with ninth-wicket stand of 43 before the former was superbly caught behind for 33 by Adam Wheater, standing up to the stumps for the bowling of Ravi Bopara.
And it was Harmer who then ended the game as Morkel (21) attempted a lofted hit down the ground but was bowled.