Alex Johnson's emotional return to the AFL will give his Sydney teammates a lift against Collingwood on Saturday night, but they haven't forgotten how important the result is to the club's season.

Midfielder Harry Cunningham was one of the first Swans to find out that Johnson would be making his long-awaited comeback against the Magpies at the SCG, his first senior game since the 2012 Grand Final.

Cunningham made his debut against Greater Western Sydney in round one that season, but it was his only game of the year, meaning he hasn't played with Johnson since.

This week's must-win clash with the Pies will be the 24-year-old's 100th senior match, and he said on Thursday having Johnson in the line-up will make it a night to remember.

But Cunningham stressed that reversing their worrying form trend was more important for the Swans, who have lost four of their past five matches to drop to ninth on the ladder.

"I think Alex playing will give us that extra boost," he said.

"To run out alongside him on the AFL stage for the first time in a long time will be special, and it just adds another element to Saturday night.

"As expected he's pretty excited, but once we run out we'll just be looking to play our role and play a good game of footy.

"We've just got to get back on the horse and start firing again, and as players we're in control of getting that done.

"I wouldn't say it's a reset, we've played some really good footy this year, so we just need to get back to that." 

Wagga-born Cunningham is yet another former rookie to forge a career in the AFL, and as one of the lower profile players on Sydney's list he said he wasn't upset to have his milestone upstaged by Wednesday's announcement of Johnson's return.

"I'm pretty happy that 'AJ' stole my thunder, I'm more of a 'fly under the radar' sort of guy," he said with a laugh.

"I'm pretty close with him so I was absolutely stoked to hear the news.

"I saw him on Wednesday and I knew something was up.

"He was up and about a bit more than usual and he told me, so it was a pretty special moment to share with him."

The Swans will wear a commemorative jumper in Saturday night's match, celebrating the 100-year anniversary of the club's 1918 premiership side, when South Melbourne defeated Collingwood to win their second VFL flag by five points at the MCG.