Brandon O'Neill's opener was cancelled out by Ulises Davila midway through the second half before Grant produced his memorable 77th-minute game-winner.

Five days after helping the Socceroos to a six-goal win in Taiwan, Grant flicked a Brandon O'Neill free kick over Stefan Marinovic and just under the crossbar.

It was a cruel defeat for the visitors, who controlled large chunks of the contest against a Sky Blues side that lacked ruthlessness once ahead.

Ufuk Talay's team also ended the night with 10 men after Liberato Cacace was marched for an ugly challenge on Anthony Caceres in the 79th minute.

The frustrating escape ensures Sydney open their championship defence with back-to-back victories, while the Phoenix will rue a second straight close defeat.

It also means the Sky Blues remain atop the ladder alongside Western Sydney, setting up a mouth-watering first derby at Bankwest Stadium on Saturday.

Sydney coach Steve Corica paid tribute to assistant Robert Stanton, who has been the architect behind their set pieces this season.

Stanton took over from Talay, who moved across the Tasman during the winter.

"(Stanton) is doing a great job with the set pieces and when you score set-piece goals. It helps out with the attack obviously, when we need it as well," Corica said.

"Both games we've scored set pieces at the right times."

Playing in their first home game of the season, the defending premiers were welcomed by a heaving Leichhardt Oval crowd of 12,536.

The cove's tifo was a caricature of four former and current stars and a fifth silhouette with the message, 'Which of you is next?'

The Sky Blues responded with an immediate array of sharp passing, particularly through their right-side combination of Alex Baumjohann and Grant.

Their dominance was converted into the opener for O'Neill, who was given ample time to shift to his left following a weak clearance from a corner.

But while the early indications were of a cruisy afternoon, what followed wasn't.

Sydney took their foot right off the pedal and the opportunities slowly accelerated for Wellington, who finished with four more shots at halftime.

Jaushua Sotirio had the best of them moments before the break, with his powerful header that drew a diving save from Andrew Redmayne.

The Phoenix gradually grew in confidence and were unlucky not to draw level when David Ball's 50th-minute snap hit the inside of the post and across goal.

The visitors were finally rewarded for their persistence in the 69th minute when Sotirio cut back for Davila, who shifted to his left and angled past Redmayne.

But the hosts reclaimed the lead against the run of play on Grant's heroics, before holding on in the final 13 minutes for a gritty triumph.

"I thought we had them on the ropes. We equalised, and obviously the send-off hurt us, going down to 10 men," Talay said.

"Very proud of the performance, to come here against last year's champions and put on a performance like that."

Australian Associated Press