But he top scored with 68 as Portsmouth - asked to chase a slightly rain-reduced target of 256 off 48 overs, after Ventnor had posted 260 - won by five wickets with 19 balls to spare at Steephill.
Portsmouth’s reply began badly when skipper Ben Duggan, playing against his former club, was out for a second-ball duck. And it was 21-2 when Zack Wells (2-20) claimed the scalp of James Mitchell (15).
Opener Jack Marston (55) and Jalill set about repairing the damage with a third-wicket partnership of 124.
There was still much work to be done at 161-4 with both of those batters back in the pavilion.
But Daniel Wimble and Sujeeth Daini promptly produced a match-winning partnership of 83 for the fifth wicket.
With Portsmouth behind the run rate, they clubbed 60 off five overs - including 16 off the 40th, 13 off the 38th and 12 each off the 41st and 42nd - to relieve any run chase tension.
Though Wimble fell for a 43-ball 35, Daini was still there at the close - unbeaten on a SPL best 57 off 30 balls with five fours and two sixes.
It was left to Joe Kooner-Evans to bring up victory with a single off the penultimate ball of the 45th over.
The second tier’s leading runscorer, Dineth Thimodya, had earlier taken his Division 1 tally to 446 at 74.73 with 87.
The Sri Lankan shared an opening stand of 108 with Rob Snell (60) before the latter was bowled by Jalill, the fifth bowler Duggan had utilised.
Thimodya struck eight fours and four sixes and was within sight of a third SPL ton of 2022 when his stumps were rearranged by Rakshith Rao (2-50).
Reuben McArdle (3-44) was Portsmouth’s most successful wicket-taker as Ventnor, who had chosen to bat, amassed 260-9 from their 50 overs. McArdle now has 17 Division 1 wickets - only Alton’s Bash Walter and Liam Carty (Calmore) have more (20 apiece).
Sam Floyd was dismissed in the 80s for the second week running as Sarisbury handed second from bottom Sparsholt a 131-run home thumping.
A week after hitting 83 against New Milton, Floyd struck 89 as Athletic posted 286 after being inserted at the Norman Edwards ground.
Floyd had cracked 14 fours and two sixes at exactly a run-a-ball until he was clean bowled from the 90th delivery he faced. No 7 Rob Franklin (52) and skipper Josh Hill (41) were also in the runs.
In reply, Sam Hill (3-35) and Jordan Wright (3-38) were among the wickets as Sparsholt crashed from an already troublesome 92-4 to a sickly 96-7.
Callum Doran (50) top scored at No 6 but he was ninth out at 143 with the final wicket tumbling 12 runs later.