Jofra Archer showed no ill effects from the side injury which troubled him throughout the World Cup during four overs during which he picked up the wickets of Surrey’s top scorer Ollie Pope(43) and Aaron Finch (6).
The 24-year-old had Finch well caught on the square-leg boundary by Delray Rawlins. He returned in the 14th over with a superbly disguised slower ball to dismiss Ollie Pope, who had just hit four boundaries in an over off Danny Briggs and appeared to be guiding Surrey to victory.
Surrey looked the favorites to win with 29 runs needed off the last five overs with five wickets in hand but Tymal Mills dragged Sussex back into contention when two searing yorkers taking the wicket of Tom Curran (19) and Ryan Patel (0) in the 18th over.
Then off the final ball of the 19th over, Rikki Clarke holed out to long-on, leaving ninth-wicket pair of Imran Tahir and Gareth Batty with the task of scoring 12 runs from the last over from David Wiese, who was bowling his only over of the night.
Wiese conceded singles off the first two deliveries then Tahir stylishly upper-cut a full toss for six runs. Two runs came off the next two deliveries, leaving Batty to score three to win off the final ball. He drove to long-on and the pair scrambled back for a second after Sussex missed with two throws at the stumps, either of which would have run him out had they been on target.
Earlier, Sussex had finished on 144 for 8 after skipper Luke Wright and Phil Salt had smashed 50 in the first four overs.
Salt, dropped by Curran off his second ball, hit 27 off ten balls including successive sixes off Jade Dernbach. But the Sharks were never the same when he holed out later in the same over and it needed an unbeaten 76 from skipper Wright to get them to a competitive total.
Sussex only managed six boundaries after the sixth over with Wright unable to go onto the offensive because wickets were falling too regularly at the other end. Veteran off-spinner Batty had figures of 3 for 8 at one stage while only Ben Brown (10) got into double figures. Wright hit 14 off Jordan Clarke in the 18th over and finished with 76 off 59 balls including nine fours and a six.