The Coptermen appeared on course for their first Senior Division victory against Grove since November 2016 when Sam Chandler’s 17th minute header gave them an interval lead at Marsden Road this evening.
But it was an advantage claimed against the run of play as Grove had carved out the better chances in the opening 45 minutes and should have been in front.
As it was, they required a double from Cornish - playing his first league game of 2021/22 - to give the hosts a deserved three points and extend Fleetlands’ winless streak against Grove to eight matches.
Grove should have been ahead within the opening minute, Louis Tyler’s shot clipping the bar from within the 18-yard box when he should really have hit the target.
Cornish went close on 16 minutes, getting on the end of a right-wing cross but his effort rolling inches wide.
Fleetlands responded by going up the other end and taking the lead with their first on-target effort.
Striker Kelvin Robinson delivered an inviting cross from the right flank and Chandler was left unmarked at the far post for the easiest of headers past Taylor Revy.
Grove continued to attack, Cornish sending a 25-yard free-kick just wide and teenage keeper Harry Page turning a shot from Michael Baker - the Bognor Regis striker on loan at Horndean - away for a corner.
Cornish was close with a header and Preston Tee’s 25-yarder was straight at Page as Grove poured forward.
After ex-Grove HPL title winner Tommy Woodward had a low shot through a crowded goalmouth booted away by a home defender, Cornish again went close. This time Baker collected possession after Page had raced out of his penalty area, setting up the former Baffins Milton Rovers player to fire just over the bar.
On a breakaway, Revy was called into action, saving with his legs after the pacy Robinson had collected a long ball and advanced into the 18-yard box.
It was no real shock when Grove finally levelled just before the hour mark.
Literally seconds after Fleetlands boss Rich Bessey had thrown on his first subs, Jamie Wrapson and Glynn Cooper, left-back Jordan Cheung floated in a free-kick which Cornish nodded in at the far post.
Seven minutes later, Cornish produced a superb piece of skill to give Grove the lead - sending an angled chip over Page, who isn’t the tallest of keepers, and into the far corner.
It was a goal worthy of winning a game, and so it did.
Jake Alford wasted a free-kick in a good position for Fleetlands, sending his effort well over the bar from a central position, and Robinson twisted and turned in the area before also shooting wide from the visitors’ best chance late on.
Cornish fancied a hat-trick, collecting a long ball and shrugging off a challenge only to send a fierce 30-yarder whistling over the bar.
Grove boss Wayne Grant picked up a late booking for comments made to referee Des McCullough, but the final whistle shortly after gave his side a second win in four days against a potential title rival.
The fixture list had not been kind to Grove, with key players missing at the start of the season including striker Danny Lane, with their first three games at home to Moneyfields Reserves, Locks Heath and Fleetlands.
Those are the three teams, according to Grant, that along with his own side should be looking to finish in the top four.
Though Moneys claimed a deserved 2-1 success at Marsden Road, Grove followed up with a 1-0 victory over Locks and this win against Fleetlands is further proof they will surely be one of the top sides in 2021/22.
Paulsgrove: T Revy, Dorsett, Tee, Mallory, Butcher, Ralph (Martin, 70), Cheung (Lewis, 76), Fennemore, Tyler, Baker, Cornish.
Fleetlands: Page, Sims, Winter (B Cooper, 65), Martin, Heard, Easton (J Chandler, 77), Alford, Maunder (Wrapson, 58), Robinson, Woodward, S Chandler (G Cooper, 58).