Ravi Bopara's superb 115 not out from 94 balls, well supported by 65 from Greg Smith, swept Essex Eagles to a seven-wicket win against Surrey at the Kia Oval which keeps them well in contention in Yorkshire Bank 40 Group B.
Essex hunted down Surrey's 223 for seven with 4.5 overs to spare for a fifth victory in the eighth of their 12 round-robin group matches.
Bopara and Smith came together at 15 for two, after Mark Pettini was caught at cover for five and Hamish Rutherford athletically held at the wicket on nine, and their stand of 152 in 25.3 overs was a perfect demonstration of controlled acceleration.
It was also an Essex third-wicket record against Surrey in all List A cricket and when Smith skied his 77th ball, from Jon Lewis, to deep mid-on in search of a fourth six it merely signalled a final onslaught from Bopara and Ryan ten Doeschate, who added a further 59 in 4.3 overs.
Bopara reached his 90-ball century during a 34th over which cost left-arm spinner Zafar Ansari 21, as the England man and ten Doeschate hit a six and a four apiece.
Surrey, with virtually no chance of qualification for the semi-finals next month, opted to play a youthful team and rested key one-day players Jade Dernbach, Azhar Mahmood, Gareth Batty and Steven Davies ahead of Tuesday's Friends Life t20 quarter-final against Somerset.
One of two teenagers given a senior debut, 17-year-old batsman Dominic Sibley, had a game to forget after being stretchered off with a badly cut knee early in the game.
Sibley, still at Whitgift School, suffered a two inch gash as he dived for the crease to avoid being run out during the fourth over of Surrey's innings and, after completing another single when partner Vikram Solanki called him for a run several balls later, he signalled to the dressing room that something was badly wrong.
The game was held up for almost 10 minutes as Sibley, who had made two runs from seven balls faced, was first treated and then hoisted on to a stretcher. He left the ground immediately to go to hospital.
Solanki went on to top-score for Surrey with 86 from 95 balls before being bowled swinging at Reece Topley at the start of the 35th over.
Jason Roy fell for four just before the Sibley injury incident, caught at slip off Graham Napier, but Gary Wilson added 71 with Solanki and hit left arm paceman Tymal Mills for six in a 46-ball 31 before being held on the deep square-leg boundary mis-hitting a pull at the same bowler.
Ansari swung left arm spinner Tim Phillips over midwicket for six in a brisk 31 from 36 balls, and Rory Burns struck an unbeaten 39 from 25 amid a clatter of late wickets in the closing overs, with a pulled six off Napier and three fours.
Tom Curran, the 18-year-old son of former Zimbabwe all-rounder Kevin Curran and Surrey's other debutant, was run out second ball for one by Bopara's direct hit from mid-off.