Surrey kept alive their hopes of reaching the Friends Life t20 quarter-finals as they got the better of a high-scoring affair with Sussex to win by 18 runs at Whitgift School.
Stephen Davies led the way with the bat for the Lions as he cracked an unbeaten 99 from 56 balls to help the hosts post a commanding total of 203-2 from their 20 overs.
Sussex looked right on course to chase down that score after Luke Wright (72) helped them away to a flying start, but they lost wickets at crucial points and ultimately came up short as they finished on 185-5.
With the venue hosting a Twenty20 match for the first time, former Whitgift pupil Jason Roy set the tone for an evening of big-hitting as he advanced down the wicket and crashed the first ball of the match for a six.
Roy would depart for a quickfire 18 after being deceived by a slower ball from Chris Liddle, but opening partner Davies remained and continued to send the ball to all parts as he raced to his half-century off 29 balls.
Skipper Rory Hamilton-Brown joined him at the crease and brought up his side's 100 just past the halfway point of the innings as he flicked away Umar Gul for a boundary.
Hamilton-Brown registered his own half-century after seeing an inside edge race away fine for a streaky four, but Chris Nash got his revenge the very next ball, bowling his former team-mate as he skipped down the wicket.
Sussex did not help their own cause as they contrived to drop Tom Maynard no fewer than three times - Wright once and Ben Brown twice - and the right-hander made them pay as he combined well with Davies, making a brisk 29 to help his side past the 200-mark.
But Wright and Brown did combine well at the top of the order for Sussex with the former in particularly explosive form as he smashed his way to 50 off just 21 balls - back-to-back sixes off Zander de Bruyn getting him to his half-century.
With a hundred on the board after just 8.2 overs the Sharks looked well-placed, but Chris Schofield picked up the much-needed wicket of Wright as the England man went for another big hit and was caught on the boundary rope by Stuart Meaker.
Surrey then managed to apply the brakes as the spin of Schofield and Zafar Ansari proved difficult to get away with Matt Prior (four) falling cheaply to Schofield.
Indeed, it was only Brown keeping the Sharks in the contest as he continued to go well, but when he departed for 68 off 52 balls courtesy of a brilliant catch from Roy in the deep the game was all but up for the visitors who needed 36 from 9.
Despite the best efforts of Nash, puzzling demoted behind Wayne Parnell in the batting order, Surrey saw out the game with Meaker's final over proving more than good enough.