Sussex 213 for 7 (Alsop 68, Hughes 65, Curran 3-23) beat Surrey 177 for 7 (Pope 99*, McAndrew 3-32) by 36 runs
Sussex Sharks handed Surrey their first defeat in this season's Vitality Blast with an impressive 36-run success at the Kia Oval.
Tom Alsop's 36-ball 68 and 65 off 42 deliveries by left-hander Daniel Hughes helped power Sussex to 213 for 7 after they had been put in - their biggest score in the format against Surrey.
Skipper Ollie Pope led Surrey's response with an unbeaten 99 in a total of 177 for 7, but Sussex bowled with more discipline on a used pitch. Their spinners sent down eight overs and both Archie Lenham and James Coles picked up important wickets while Australian seamer Nathan McAndrew took 3 for 32.
It was an excellent performance by Sussex, whose decision to shunt Alsop down from three to six in their order paid off handsomely.
He added 47 in four overs with Hughes when the Australian fell for 65 in the 12th over to a well-judged running catch by Jason Roy.
But Alsop maintained Sussex's momentum with McAndrew as they thrashed 68 in six overs for the sixth wicket.
Alsop passed 50 in T20 for only the eighth time in his career as all of the Surrey seamers struggled with the exception of Tom Curran, who finished with 3 for 23 despite conceding 17 off his final over.
Hughes helped himself to four boundaries in one over from Gus Atkinson while at the start of the innings Coles, promoted to No3, had taken Jordan Clark for three successive fours before walking across his stumps to Clark's leg-stump yorker.
It was one of three wickets Sussex lost in the powerplay, but they were still progressing at more than ten an over and even when Curran picked up John Simpson in the eighth over to leave them 68 for 4 they kept on swinging.
Hughes played proper shots on both sides of the wicket in a controlled display while the outstanding Alsop hit eight fours and three sixes, the second of which - a pull from outside off stump off Gus Atkinson - took the left-hander to a 25-ball fifty.
McAndrew's cameo at the end of 29 from 15 propelled Sussex past 200 and the question then was whether their varied attack could blunt Surrey's quality batting unit.
Both openers had gone inside four overs. Ollie Robinson's nip-backer was too good for Laurie Evans and Dan Lawrence was well caught by the diving Fynn Hudson-Prentice at deep third off a thick outside edge.
Roy and Pope rebuilt in a stand of 73 but Sussex were more disciplined with the ball as Coles, 20, and 19-year-old Lenham prevented Surrey from accelerating.
The required rate had climbed to 15 an over when Roy, starved of the strike, holed out to long-on off Lenham in the 13th over. The leg-spinner was then taken for three sixes off the next four balls, but he'd made a crucial breakthrough.
Smith briefly threatened before toe-ending a drive to wide long-on and 77 off the final five overs proved beyond even Pope's capabilities, although he did have the consolation of reaching his maiden century in the final over, from 60 balls with ten four and three sixes. Sussex, though, thoroughly deserved their second win from three games.
