Surrey 189 for 9 (Jacks 86, Harmer 3-44) beat Essex 176 for 8 (Rossington 78, Jordan 3-34) by 13 runs
Will Jacks hammered five sixes in a scintillating 86 to consolidate Surrey's place at the head of the Vitality Blast South Group and guarantee a home match in the quarter-finals.
Jacks hit five sixes in his 46-ball knock and put on 63 in five overs in a stand with Jordan Clark that constituted a record for the sixth wicket against Essex. That rescued Surrey after they suffered a mid-innings collapse before the reset that helped them post 189 for 9 and eventually prevail by 13 runs.
Surrey had struggled against the Essex spin pair of Matt Critchley, who took 2 for 22, and Simon Harmer, whose 3 for 44 was a season's best. Paul Walter chipped in with two late wickets to finish with 2 for 26 to take his tally to 15.
Adam Rossington tried manfully to take Essex to a third win in four days, and qualification for the knockout stages, but he fell for a 49-ball 78 with five sixes and with it went home hopes. Essex now need at least a point from Friday's final match at Hampshire to reach the quarter-finals.
Chasing 190 to win, Essex lost Dean Elgar in the third over as he slapped Clark to cover point, but that was before Rossington and Michael Pepper got moving. Sam Curran was lofted for sixes by both batsmen in one over to square leg as they put on fifty inside five overs.
When he reached 12, Pepper, a centurion at Hove 24 hours earlier, passed 500 runs in this season's Blast. But he had added just 15 more when he skied Cameron Steel to short extra cover. Steel struck again five balls later when he bowled Charlie Allison with one that kept low.
Steel had piled pressure on Essex by conceding just seven runs in his first two overs before Rossington smashed him for six over long-on shortly after he reached a 33-ball fifty.
Clark got lucky with a full-toss that Walter hit vertically into orbit, giving Rory Burns time to run round and take the catch in front of the stumps. And Critchley followed quickly when he lifted Chris Jordan to deep midwicket.
However, with Jordan and Curran both conceding single-figure overs, the required run-rate rose towards 15 with 47 runs needed from the last three overs. And that became an impossible target when Rossington fell to the third ball of the 18th over, flailing Curran to the mid-off boundary.
Surrey, put in on a used wicket, moved along serenely initially, reaching the end of the powerplay at 62 for the loss of Dom Sibley, lbw to Shane Snater to one that kept low. However, the stuffing was knocked out of their stride when Critchley and Harmer shared three wickets in eight balls and stemmed the mid-innings runs.
Laurie Evans was first to go, bowled by one that turned appreciably from Critchley before Harmer accounted for Burns and Curran in consecutive balls. Burns was beaten by on the outside of his bat to dislodge his stumps and Curran misjudged his first ball and was lbw.
Jamie Overton was typically belligerent, hitting a six off Luc Benkenstein over midwicket and smashing another past the bowler for four. But he then picked out Eathan Bosch on the long-off boundary to give Critchley a second wicket.
All the time Jacks was quietly accumulating. He had already swept Harmer for a huge six, launched Snater for another, and reached his half-century from 28 balls with a straight maximum off the Essex captain.
Jacks hammered Harmer for two more sixes off successive balls but departed to the next ball trying for a third, caught on the boundary at cow corner. But his sixth-wicket stand with Clark got Surrey back on track.
Jacks's departure signalled another clatter of wickets as Clark, Jordan and Tom Lawes all fell to catches in the deep.
