The Bognor Regis Town regular scored all the consolations in an entertaining 5-4 Hampshire Premier League loss to Fleetlands at Cowplain School.
Leigh’s early brace gave Grove a 2-0 advantage, but it was 2-2 at half-time and Fleetlands were 4-2 in front by the time he completed his treble.
In an end to end Senior Division encounter, Fleetlands restored their two-goal advantage before Leigh - playing four tiers lower than he normally does for the Rocks - scored his fourth.
Keeper Jayden Ridout tipped a late shot from sub Keith Martin onto the bar as the Coptermen celebrated their first league win against Grove since November 2016.
Grove boss Steve Ledger drafted in Leigh - who he knows well from their time together at Baffins Milton Rovers - following a raft of withdrawals.
The likes of top scorer Shane Cornish, Danny Lane and Frankie Kemp were all unavailable, and Grove even had to call off their Hampshire Combination reserve game as they were so short of numbers.
Tom Doughty and Jake Pepall, who had been due to play for the second team, were handed only their second first XI starts of the season.
New-look Fleetlands only fielded two of the side that had started August’s 2-1 league loss at Grove - right back Perry Easton and midfielder Stu Maunder.
Two ex-Hayling players - Josh Watts and Dan Clasby - were handed only their second starts while another former Humbug, George Gregory, made his debut. Callum Theobald and George Claister - who have also followed new Fleetlands joint-boss Dan Greenwood over from the island - were introduced as second half subs.
Gregory was to cap his first appearance with a brace as part of a lively front four that look capable of giving most HPL teams problems.
Ridout was the busier keeper to start with, saving from Harry Tindale, Leigh and Pepall. At the other end, though, Gregory had probably the best opening of them all - Taylor Revy staying on his feet to save well.
It never looked like remaining 0-0 for long, and on 19 minutes Leigh ran onto a through ball before calmly finishing.
Revy pulled off a fine close range stop from Jamie Wrapson before Leigh effortlessly drifted past two challenges in the Fleetlands penalty on his way to making it 2-0 just before the half-hour mark.
On 34 minutes Leigh should really have completed a rapid treble. He found himself in acres of space just inside the 18-yard box but Ridout rushed out to block with his feet.
It would prove a key moment in the game as, within eight minutes, Fleetlands were level.
Alpay Ali entered the game having belted 13 goals in three matches - six for the reserves against Liss reserves, four against Hamble United in the Hampshire Trophy and three in a 10-2 league rout of Liss.
And the former Gosport Borough attacker was to continue his purple patch, scoring twice to take the teams in level at half-time - the second after latching onto a back pass.
Fleetlands could easily have been leading at the break, with Smith taking an Ali pass and firing just wide from a good position.
Grove were forced to make a change just before half-time when Pepall limped off - replaced by Jordan Cheung - after being injured by a sliding tackle from Clasby just outside the Coptermen penalty box.
Ledger was furious that no foul was given, and no card shown to the centre half. Indeed, the only yellow shown was brandished to the Grove boss for comments made to referee Mick Ridge.
Fleetlands required only two minutes of the second half to complete the turnaround, Wrapson finishing off a sumptuous Callum Smith cross with an equally fine shot that gave Revy no chance.
It was 4-2 on 62 minutes when Ali set up Gregory for a simple tap in. Grove, though, were not finished and Leigh - a peripheral figure in the second period up to this point - completed his treble seven minutes later.
Ali and Smith combined down the right to produce another tap in for Gregory, taking his seasonal tally to 15 and four in two games after a brace on his last Hayling appearance against leaders Moneyfields.
Poor defending gave Leigh the chance to tap his fourth goal into an empty net and set up the proverbial grandstand finish.
And honours would have ended even had Ridout not tipped Martin’s effort onto the crossbar in the last attack of a thoroughly enjoyable game.
Enjoyable if you were a neutral or involved with Fleetlands, of course!
Fleetlands: Ridout, Easton, Rogers, Clasby, Shadbolt, Watts, Maunder, Wrapson, Ali, Smith, Gregory. Subs used: Sims, S Martin, Theobald, Caister.
Paulsgrove: T Revy, Dorsett, Scott, Mallory, Butcher, C Revy, Austin, Doughty, Tindale, Leigh, Pepall. Subs used: Warlow, Cheung, K Martin.