A topsy-turvy match at Wellington's Sky Stadium on Saturday swung on two key moments from Phoenix keepers past and present.
On six minutes, Sail, who captained the club at times last season but left for Perth in the off-season, had a horror moment, clearing to Phoenix striker Oskar Zawada.
The Polish forward had plenty to do but quickly lobbed the retreating Sail from 35 metres.
Wellington held an advantage into the dying minutes, with attacker Bozhidar Kraev scoring in the 74th after Glory captain Mark Beevers headed a 59th-minute equaliser.
The Nix looked to have squandered their lead with Lukas Kelly-Heald inexplicably handballed a harmless cross just before it crossed the goal line.
Instead, Paulsen - just 21 and on his home debut - saved low to his right from former golden boot winner Adam Taggart's penalty as Wellington clung on.
The result gives new coach Giancarlo Italiano a first win as Phoenix coach, having replaced Ufuk Talay in the off-season.
There were signs of an exciting passing game in development under Italiano in Saturday afternoon's distance derby, attended by 6101.
However, Perth - also under new boss Alen Stajcic - were stronger for long spells in the middle of the match.
Wellington should have had at least a couple of first-half goals, with hard-running Tim Payne cutting inside and missing the target from close range, and Kraev striking the base of the post from a cut-back from Kelly-Heald.
As the half wore on, Perth wrestled back momentum, and might have had an equaliser if not for Payne.
On 40 minutes, Paulsen fumbled a shot from David Williams - on for the injured Luke Ivanovic after just a quarter-hour - through his legs, requiring Payne to clear as the ball trickled towards the net.
A halftime pep talk from Stajcic and the injection of Stefan Colakovski kept Glory on top after the break and on the hour mark, they were on level terms.
Beezers rose unchallenged in the box to head Oliver Bozanic's well-weighted free kick past a static Paulsen.
Kraev's strike would prove to be a winner, the Bulgarian finding himself on the end of a breakaway started by Ben Old's terrific midfield interception.
Sail's mistake is the second in two starts for Perth, after poor judgement at a cross late in their round-one draw with Newcastle gifted the Jets an equaliser.
