Holders Horsham were knocked out of the T20 Cup by rivals Roffey in a semi-final showdown on Sunday.
In the rearranged match, it was the Boars that clinched a 41-run success to book their place at Hove on finals day against Preston Nomads.
It was the second attempt to play the game after the initial fixture was controversially rained off last month – with the other last-four game decided with a bowl-out.
And Roffey made up for some of the disappointment less than 24 hours previously when the Premier Division fixture between the two sides was abandoned due to the weather at Cricketfield Road.
That gifted pole position back to East Grinstead, who eased to a seven-wicket success against Bexhill.
In the cup clash, Roffey lost the toss and were inserted and set about making 166-8 in their 20 overs.
Openers Ben Manenti (34) and captain Matt Davies (44 including one four and five sixes) put on an opening stand of 59 before the former was bowled by spinner Michael Munday. Usman Khan (27) and Davies took the score to 99-2 and Rohit Jagota (31) boosted them to 155-4.
A flurry of wickets, thanks to the continued bowling of Munday (5-14 from his four overs) saw then next four wickets fall for just 11 runs.
In reply, Ryan Maskell (44) got the hosts off to a good start. And while Tom Haines (five) and Tom Johnson (two) fell cheaply, Maskell and captain Michael Thornely (31) took them to 97-4.
With the game in the balance, only Nick Oxley (20) and Mika Ekstrom (ten) made double figures as Horsham were bowled out for 125 with two balls remaining.
Abdul Khan was the main tormentor with the ball, claiming 5-21 from three overs as Manenti and Luke Barnard had claimed two scalps each.
Roffey coach Simon Fearnley revealed the minimum score they looked to set batting first was 160 and said: “If we get that we are asking our opponents to score eight an over for 20 overs and I believe in our bowling unit to defend that and get us over the line.
“I think Davo (Davies) was a tad disappointed, especially after that way that he and Ben started with the bat, followed by Rohit and Usman, that we didn’t get to the 180 mark.
“Abidul had a great spell with the ball. His cluster of wickets really did turn the game on its head. It was as important as the batting in the top order.
“I thought it was a really good solid team performance from all the players. We batted well up top, fielding was solid, the catching was good and bowled effeciently.”
Thornely said: “Roffey played better than us on the day. They were probably 20 runs above par with the slow outfield and they hit five more sixes than us.
“When we batted we weren’t able to hit the boundaries as regularly as they did and ultimately this was the difference.
“We got off to a good start with Ryan Maskell playing an excellent knock. Ultimately they played better cricket in both power plays than us and unfortunately that meant we had a little too much to make up when the field was spread.”