Surrey will play Northants in the Friends Life t20 final after upsetting favourites Hampshire in the second semi.
After restricting the defending champions to 142-9, Surrey always looked on track to chase down their target and did so with four balls to spare.
Needing 18 runs from the last two overs, Zafar Ansari effectively ended the contest with a burst of six, two, four in three balls off Chris Wood's final over.
First, he smashed the bowler over his head for a straight six, before scampering two more off the next and then hitting a full toss straight down the ground as Surrey took 15 from the over.
Ansari (21 not out) wrapped it up by pulling Sohail Tanvir for four to fine leg off the second ball of the final over as he and Zander de Bruyn (41 not out off 40) put on an unbeaten 33 for the seventh wicket after they'd fallen to 112-6.
Surrey paceman Azhar Mahmood was voted man-of-the-match after a superb spell of bowling kept the defending champions in check.
The miserly Mahmood conceded just nine runs off his four overs and took the wickets of Hampshire skipper Dimitri Mascarenhas and Sean Ervine, who was threatening to rescue the Northants innings after moving onto 47 with three sixes and two fours.
Northants, who were put in after Surrey won the toss, never really got going after Jon Lewis removed dangerman Michael Carberry for just six after the opener picked out Jason Roy at point with an uppish drive.
Apart from Ervine no other Northants batsman passed 19. Jade Dernbach bowled James Vince with his very first ball and also grabbed another wicket with the final ball of his opening over when trapping Neil McKenzie leg before although Hawk Eye suggested the ball was missing leg stump.
Defending 142 was always going to be an uphill task for Hampshire and their bid to win this tournament for the third time in four years always looked as if it would end in failure.
Wood and Mascarenhas had both openers back in the hutch with the score on just 17 but useful contributions from Glenn Maxwell (26), Vikram Solanki (19) and Gary Wilson (15) kept the scoreboard moving before de Bruyn and Ansari saw Surrey over the line.