Sohail Tanvir's devastating early burst of pace bowling enabled one-day specialists Hampshire to leapfrog Essex to second in Yorkshire Bank 40 Group B with a 30-run win at the Ageas Bowl.
Pakistani all-rounder Tanvir dismissed the first three in the Essex order in his first three overs as Hampshire successfully defended a modest total of 216 after being put in by Essex captain James Foster.
Graham Napier, Greg Smith and Ryan ten Doeschate led a brave revival and while Napier was swinging away in typically aggressive style, hitting sixes off Tanvir and Danny Briggs, there was hope for Essex.
At 180-7 with three overs remaining an unlikely Essex win was not to be discounted but left -armer Chris Wood came back to remove David Masters and Napier in the 38th over and Tanvir fittingly came back to get rid of last man Reece Topley with the first ball of the last over from which the visitors required an almost impossible 31.
Tanvir finished with figures of 4-29 as reward for setting up Hampshire's sixth win in eight group fixtures in the same week as the club booked its place in the semi-finals of the T20 competition at Edgbaston for the fourth successive year.
As holders of both titles, Hampshire showed they know how to win tight finishes and after losing the prolific Michael Carberry in the second over to a slip catch off Masters, they fought back through James Vince as wickets tumbled around him.
Tymal Mills, Topley and Masters each took two wickets and at one stage Hampshire were in trouble at 148-8 with top-scorer Vince among the departures, caught at the wicket off Ten Doeschate for 68 from 75 balls.
Former Essex batsman Adam Wheater led a late charge with a stand of 64 for the ninth with Wood before being run out, backing up in the last over.
Foster will have cause to remember the match with affection despite the result, taking five catches and stumping Liam Dawson who had been lured from his crease by spinner Tim Phillips.
Essex were soon in a dire position, Hamish Rutherford was bowled in Tanvir's first over, Ravi Bopara went in his second and Mark Pettini followed to leave them 14 for three after five overs.
Smith and ten Doeschate attempted a rescue with a stand of 71 for the fourth wicket in 17 overs but at 142-7 it looked to be all over for Essex with only nine overs left.
But Napier is never to be underestimated in such situations and with Masters as a willing aid, the eighth wicket pair caused Hampshire hearts to flutter in a productive stand of 42 in six overs.
Only then did Wood and Tanvir return to the attack and the Essex challenge died as Hampshire went above them in the table.