Essex 187 for 6 (ten Doeschate 82, Butler 3-23) beat Nottinghamshire 140 (Hussey 61, Tait 4-29, Masters 3-26) by 47 runs
Nottinghamshire suffered a third consecutive quarter-final defeat after Shaun Tait stole the spotlight from Ryan ten Doeschate with a stunning hat-trick to end the home side's already fading hope of derailing Essex's charge towards a fourth appearance at Twenty20 finals day.
Ten Doeschate's 82 from 44 balls, with support from Ravi Bopara in a stand of 72 for the fourth wicket, enabled Essex to overcome a slow start and leave Nottinghamshire to chase their biggest target of the season.
It was a chase they began at what looked like a winning tempo, racing to 50 without loss in only 21 deliveries as Alex Hales and Michael Lumb, the latter having ridden his luck when an edge off Graham Napier's first ball flew through the hands of Mark Pettini at slip, looked in the form to dominate.
But when David Masters dismissed both openers in his opening over, Hales finding Greg Smith at deep midwicket after smashing 31 in 13 balls before wicketkeeper James Foster, standing up, took a sharp catch to remove Lumb, the balance dramatically tilted in Essex's direction.
In only two of the next 11 overs did Nottinghamshire manage to score in double figures as one Essex bowler after another found the ability seemingly to hit yorker length at will, giving so little opportunity to score that after reaching the halfway point at 87 for 4 - 13 in front of where Essex had been - the next five, crucial overs passed without a single boundary.
Samit Patel had looked out of sorts, contributing only 2 from 12 balls and with 70 needed from the final five, skipper David Hussey indicated to his fifth-wicket partner Riki Wessels that the all-or-nothing point had been reached and promptly despatched ten Doeschate for six over deep midwicket. But the plan began to unravel immediately when Wessels was brilliantly caught on the same boundary by Bopara, who managed to release the ball as his momentum carried him over the rope and allow Tim Phillips to complete the catch.
Nottinghamshire questioned whether Bopara had his foot out of bounds before he tossed the ball backwards but replays did not show conclusively that he did and the wicket stood.
It was academic in any event as the next over yielded not only Tait's hat-trick but also the run-out of Chris Read. Hussey - whose 61 was tempered by escapes on 33 and 48 - holed out to ten Doeschate at wide mid-on and Tait then had Ian Butler caught on the boundary off his next delivery before bowling Graeme White.
Commanding though their total was in the end, the Essex innings had taken a long time to gather momentum after Nottinghamshire's bowlers took a tight grip from the outset after Hussey had opted to chase. Limited to 46 in the Powerplay, they lost wickets too, Hamish Rutherford caught behind attempting to cut Jake Ball and Mark Pettini trapped on the crease by Butler in a catastrophic sixth over for Essex that saw Smith run out at the non-striker's end after Bopara changed his mind about a single to mid-on.
At halfway they were 74 for 3 but Essex then enjoyed their best spell of sustained productivity as Bopara and ten Doeschate went after the spinners, Patel and White, reaping 44 in three overs as Nottinghamshire began to suffer the effects of ten Doeschate in full flow, cursing the decision by umpire Nigel Llong to reject an impassioned appeal for leg-before by Butler when he had made only 6.
The Netherlands allrounder, twice a centurion in T20, took 27 off White in just 13 balls as Nottinghamshire's leading wicket-taker suffered one of his less-effective nights, and when consecutive sixes off Ball in the 16th over took him to 53 off 30 deliveries, Essex were sensing a competitive total.
Bopara had atoned in part for the mistake that cost Smith his wicket in full flow by scoring 38 off 24 balls before driving Ball to long-on, the fourth-wicket pair adding 72 in 43 balls. Foster fell for only 8 but ten Doeschate was seeing the ball vividly and his fifth six, driven down the ground off Butler, took him to 82 off 43 balls inside the last over before he holed out to long-on.
Nottinghamshire had attracted a record crowd of 12,106 - the highest for a home T20 fixture - but fell well short of expectations, beaten essentially in the bowling, where much as Butler and Gurney impressed, Patel (0 for 54) and White (0 for 44) were simply too expensive. By contrast, Essex's Tait and Masters, not to mention Reece Topley (0 for 12 from three) were collectively superb.