MELBOURNE stopper James Harmes believes Joel Selwood's third-quarter brain fade shifted the momentum in the Demons' favour, en route to Friday night's elimination final win.

Harmes' verbal stoush with Selwood extended into physical contact as he followed the Geelong skipper to the bench for a rest.

Engaged in a tangle on centre wing, Harmes had teammate Jake Melksham come to fly the flag, the latter drawing a high free kick from Selwood. 

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It took the ball out of Tom Hawkins' hands while he was lining up for a set shot, with the Demons able to surge forward holding a 21-point lead.

"It definitely changed the momentum of the game I think, they were lining up for goal and coming," Harmes told post-match. 

"It was a little bit of argy and bargy in one of the contests and a little bit of words between each other.

"I don't think there was too much in it. Melky got a free kick out of it so it worked out well."

Harmes kept Selwood to 14 disposals in the first three quarters before shifting to Patrick Dangerfield in the final term.

Picking up 26 touches of his own, Harmes was as influential as any Demon at stoppages, adding 11 tackles in an equal team-high with returning co-captain Jack Viney.

Having claimed Selwood's scalp in their previous meeting in round 18, holding him to a season-low 16 disposals, Harmes only needed 24 hours to prepare for another match-up.

"I actually didn't find out until yesterday (Friday)," Harmes said.

"I wasn't too sure if I'd go to Joel or Danger (Patrick Dangerfield), he's a good player and works really hard around stoppages. I thought it was a good battle tonight.

"I obviously played on him down in Geelong a couple of months ago, just went over a few clips on that. I just like to keep it simple, just want to go out there and play footy, really."

Coach Simon Goodwin praised Harmes' improvement, his rise taking him from role player across the flanks to one of the first picked in the Demons' line-up each week.

"He's done some great jobs, Harmsey, he's certainly improved as a player," Goodwin said.

"He's not only good at his defensive job that he does through the midfield but he also helps us offensively, he did a great job."

With Hawthorn ahead in a semi-final on Friday night at the MCG, Harmes is expected to get the job opposed to ball magnet Tom Mitchell.