Sydney's Isaac Heeney celebrates his side's win over GWS at Metricon Stadium in round 18, 2021. Picture: AFL Photos

SYDNEY coach John Longmire has lauded his team's "unbelievable effort" in overcoming a 35-point deficit to down Greater Western Sydney after three Swans were withdrawn from the match just an hour before the first bounce.

Callum Mills, Harry Cunningham and Colin O'Riordan were forced out of the clash between the crosstown rivals when they, along with three other Swans players and staff, were re-classified as Tier 2 contacts at the recent Wallabies vs France rugby match in Melbourne.

The Giants lost superstar forward Toby Greene and midfielder Matt de Boer for the match when nine of their players and staff were also re-classified as Tier 2 contacts.

GIANTS v SWANS Full match coverage and stats

"It was just an unbelievable effort when you consider that we probably had enough reasons just to, if we wanted to, make the choice to not keep going," Longmire said.

"The players' ability to be able to dig in and push against the tide when things weren't going well and recover and go again was outstanding.

"On top of what's already happened, to be able to have the resilience as a footy club to get through and come out the other end of it was just fantastic."

06:00

The Swans brought James Rowbottom and Dylan Stephens into the Swans' starting 22 at short notice, with Ben Ronke also added as medical sub.

All three had played in a reserves hit-out the day before the Sydney derby at Metricon Stadium, and were at the team hotel on the Gold Coast when Longmire called them with the news that they would need to back up and play a second game in two days.

Rowbottom, Stephens and Ronke arrived at the ground about 20 minutes before the first bounce.

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"We got the medical staff in and went through the players that we thought could back up, and then I rang them and told them to get in the car and come to the ground and get changed," Longmire said.

"They had to quickly get strapped and switch their heads on. And our whole meetings and all that went out the window, so it took us a bit to work it out. 

"The blokes that were told to stay out, they were great too. They kept their energy up even though they would've been flat."

ALL THE HIGHLIGHTS

Giants coach Leon Cameron faced his own challenges in the frantic period before the game including replacing match-winner Greene, who was already taking part in the warm-up when the news came through that he would have to be pulled from the match.

It's unclear how long Greene and the other players and staff who have been re-classified as Tier 2 contacts will be forced to isolate under Queensland Government directions. 

The Giants lost star midfielder Josh Kelly to a rolled ankle in the third term while Matt Flynn was forced from the ground with a dislocated shoulder in the same quarter. The ruckman returned to play five minutes before the same shoulder popped out again in an innocuous contest.

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"[Greene] is a fantastic player for us and he's had a great year. We're a far better team when he's playing for us. But whatever happens, we'll deal with it in the next 24 to 48 hours," Cameron said when asked if he was concerned about losing his talisman for an extended period. 

"There are challenges all over for the 18 clubs, we're all going through it. But it was probably more extreme tonight, 80 minutes out. 

"It didn't affect us, we started really well. We just ran out of tickets. We knew we had to have a big lead, and we did have that, but it whittled away just at the back end of the second and it has cost us."