Sussex 199 for 7 (Ward 55, Simpson 41) beat Glamorgan 172 (Douthwaite 40, Ingram 37, McAndrew 6-21) by 27 runs
Sussex Sharks completed a double over Glamorgan thanks to 6 for 21 from Australian international
Nathan McAndrew to give the visitors a 27-run win at Sophia Gardens.
A strong all round performance kept Sussex occupying an all-important top spot in the South Group of the Vitality Blast at the halfway stage.
Harrison Ward set the tone for the innings for Sussex with 55 from 24 balls inside the powerplay despite appearing to pull a muscle in the innings which prevented him from fielding. All of Sussex's top order contributed to send them to 199 for 7.
Sussex began strongly after opting to bat first with the sun still beating down at Sophia Gardens. Ward's season best despite being hampered came through a liking to Timm van der Gugten, taking 22 from the third over.
Ward's striking continued, particularly with destructive hitting straight and over deep midwicket, reaching a half-century in just 20 balls, his knock inside the powerplay thanks to van der Gugten getting his revenge with a bouncer.
John Simpson found his rhythm for a well-managed 41 from 26 balls from five off seven. Similarly James Coles, who has helped the Sharks to three wins with two unbeaten half-centuries already this season, had a license to free himself, taking Mason Crane for 19 in an over on his way to a useful cameo.
The Sussex scoring didn't let up with 10-an-over the norm after the second over until the late fightback with three wickets in four balls courtesy of Glamorgan top wicket-taker Crane and Douthwaite in the 18th and 19th overs.
Imad Wasim impressed on debut for Glamorgan and was pick of the bowlers, being the most restrictive in the powerplay, and he brought a wicket at an important time while the other spinners also played key parts with wickets and economy between them.
In reply, Glamorgan struggled to string a partnership together when chasing their highest total so far this season.
The hosts didn't find the same destructive powerplay prowess as the Sharks did, however a free-flowing
Ben Kellaway added to the newfound form of Ingram made sure run-rate was never an issue.
Kellaway had to retire hurt when he reverse-swept a ball into his helmet after damaging internationals Ollie Robinson and Tymal Mills early in his innings with swats down the ground and exquisite cover-driving.
South Africans Ingram and Chris Cooke kept Glamorgan afloat until Cook's dismissal prompted Kellaway's return. Shortly after though, Ingram and Kellaway were dismissed in the same over by McAndrew, conceding just three from the 12th over.
Douthwaite entered with the equation: 93 from 8.3 overs, immediately after the mini-collapse. The all-action allrounder, together with Asa Tribe had already put on an unbeaten 64 partnership to see them home from an unlikely position in their T20 opener. Douthwaite's five sixes in an 18-ball innings, left the equation at 41 to win from 3.5 overs.
A collapse came once more with Glamorgan going out swinging in an unlikely attempt to chase after Douthwaite's dismissal, giving McAndrew three wickets in the 19th and eventual final over.