Northamptonshire 143 (Lynn 39, Ball 4-17, Meredith 3-21) beat Somerset 126 for 9 (Smeed 49, Willey 3-17, Sanderson 3-28) by 17 runs

Reigning Blast champions Somerset were dethroned in spectacular fashion as Northamptonshire won a low-scoring thriller in the first semi-final at Edgbaston. David Willey, Northants' captain, provided the inspiration with 3 for 17 and a brilliant relay catch in the deep as the chase got close to help the Steelbacks progress to their first final in 10 years and send the holders home early.

Put into bat, Northants struggled to post 143 all out with Jake Ball taking 4 for 17 - the joint-best figures in a Blast semi. Chris Lynn made 39 off 26 but only two of his team-mates managed to reach 20, with Somerset's versatile seam attack fully exploiting a grippy surface.

The Somerset chase initially misfired as they stumbled to 12 for 3 in the third over, but Will Smeed jolted them back to life when plundering 28 from the final powerplay over, bowled by Luke Procter. Smeed fell one run short of fifty, however, thanks to a wonderful diving catch from wicketkeeper Lewis McManus, and the asking rate began to climb again as James Sales and Calvin Harrison bowled thrifty spells through the middle.

Willey picked up his third wicket of a superb showing as Lewis Gregory attempted to relieve the pressure but found long-off, and Tom Kohler-Cadmore's tortured innings of 29 off 37 came to an end in the following over. With 40 needed from 20, out came Craig Overton, the hero of Somerset's quarter-final Lazarus act at Headingley. He struck one boundary but then couldn't clear the diving Willey at long-on, a stunning flick back from over the rope all but sealing Somerset's fate.

Smeed tees off

Northants needed to start well with the ball, and they did. Willey nicked off Tom Banton first ball, before Ben Sanderson had Thomas Rew well held at deep point in the second over. When James Rew was bowled behind his legs attempting an ambitious sweep of Willey, Somerset were seemingly in trouble.

This is a battle-hardened Somerset team, however, who have seen it all before - not least when getting home from a position of 82 for 8 chasing 162 against Yorkshire on Wednesday night. They had to wait until the fourth over before Kohler-Cadmore scored their first boundary, and were still looking a bit scratchy at the end of the fifth, as Smeed twice mistimed shots off Willey that landed safely.

The introduction of Procter, in the side for George Scrimshaw, for the sixth over proved to be the tonic Smeed needed. Procter's first ball was shovelled through midwicket, his second drilled straight to long-on, the third flayed through point. Then Smeed really got going, smashing another overpitched delivery down the ground, and following up with a brutal heave over long-on for six more. He finished off with another driven four, 28 coming off the over and Somerset suddenly flying.

Northants squeeze

After Smeed's fireworks, Somerset only managed two boundaries between the seventh and 17th overs. Sales bowled four off the reel and dismissed the dangerous Smeed to finish with 1 for 16, while Harrison was equally on the money and almost put Kohler-Cadmore out of his misery earlier, only for ball-tracking to show the ball was projected to clear the stumps.

Willey's dismissal of his opposite number left Somerset 100 for 5 at the end of the 16th - needing 44 from the last 24 balls. Harrison returned to get Kohler-Cadmore, having managed just one six and one four during his stay, and the game spiralled away from Somerset after Willey's athleticism in the deep. Daniel Sams smoked one big six off Sanderson but Procter returned to redeem himself, conceding just two runs to go with the wicket of Sams in the 19th. With 23 needed from the last, Sanderson put the seal on victory, as Northants gained emphatic revenge for two heavy defeats to Somerset in the group stage.

Willey told Sky afterwards that his side were 15-20 short and needed to "take early wickets and put a squeeze on". He also paid tribute to McManus' glovework in dismissing Smeed: "Macca's catch was very much like David Murphy's in 2013 [when Northants won their first T20 title]. At that moment I thought, maybe it's our day. We talked about playing with our balls and being brave, and taking our chances. That's been something we've tried to do throughout the competition. We still shelled one today, but to take big catches in key moments, that's what is going to win you trophies."

DRS comes to Somerset's aid

Northants were quickly out of the blocks, with Ricardo Vasconcelos hitting three fours from his first seven balls and it required a slice of fortune - and an inspired review - to remove him. When Vasconcelos attempted to scoop Riley Meredith and the ball ended up at short fine leg, Somerset thought they had their man. Umpire James Middlebrook disagreed, and replays proved that the ball had only come off the thigh pad, with no bat involved; however, although Vasconcelos had jumped across his stumps, ball-tracking also showed that impact was in line and the ball would have hit the top of middle.

Craig Overton then struck in his second over. It again required the intervention of DRS, but was plumb enough that Nathan McSweeney walked off on seeing the initial replay on the big screen. When Willey miscued a hoick back over the bowler's head for 6 off eight balls - Gregory holding on despite colliding with Kohler-Cadmore - Northants were 26 for 3 and facing an uphill struggle to post a competitive total.

Ball control

Lynn, who did not face a ball until the fourth over, found his range when hauling Overton high into the Hollies Stand but Ball started his work with a maiden (that included a leg bye) as Northants finished the powerplay on 39 for 3. Lynn and Zaib attempted to reconnoiter and rebuild with a stand of 65 in seven overs, but they were only able to break free in bursts: Lynn hitting Jack Leach back down the ground and then clean over the head of deep backward square leg; Zaib, having been 10 off 16, smiting Leach straight for six more and Lynn sending another catch into the Hollies. In between, Zaib was dropped by James Rew in the deep.
The return of Ball to bowl the 12th over sent the Northants innings into a slow tailspin, as a well-executed offcutter dipped under Lynn's bat to hit off stump. Zaib's painstaking knock finally came a cropper against another Ball slower ball two overs later, and Northants floundered through the back half. They only managed to hit two boundaries from the 13th over onwards, Ball rounding out his figures with the dismissals of McManus and Procter, again to pace-off deliveries.