Reeling at 70-7 and still in trouble at 133-8, Lymington recovered with Guy Layman (80) sharing significant lower-order partnerships with Chris Jennings (22) and then Kieran Moors (45), with whom he added 98 for the ninth wicket.
But Lymington’s eventual 231 all out still looked vulnerable as Lee Harrop (77) eased Gosport’s reply to 128-1 and later 187-5.
But spells by Luke Marshall (4-40), Martin Gregory (3-39) and the inspirational Layman (2-51), whose earlier innings contained three sixes and ten fours, sent Gosport tumbling to 223 all out and an unexpected defeat.
The result leaves Lymington third in CD1 behind Shrewton and Ventnor II, who pushed their respective title claims with impressive wins.
Shrewton dismissed rivals Ropley for 155 before Sam Gillitt (67 not out) and Dan Bingley (45) eased them to a seven-wicket win.
Fifteen-year old Ben Herridge hit 93 as Ventnor piled up 304-7 before Chris Calloway’s spell of 6-34 mowed winless Rowledge II down for 93.
Tom Kent (99) and Sam Stoddart (90) shared a double-century opening partnership as Fareham & Crofton breezed past Sarisbury Athletic’s 217.
Steve Tilbury (70) was influential in New Milton’s 231-run tie at Locks Heath, while St Cross Symondians III lurched deeper into relegation trouble with a seven-wicket defeat at Ryde.
Bournemouth II were beaten by one wicket in a dramatic finish against Hook & Newnham Basics, while pre-season tips Ellingham stumbled to a 45-run defeat by Purbrook.