Harry McKay has shown a great sense of occasion with his big game and match-sealing goal for Carlton in their AFL win over St Kilda.

McKay kicked three goals and took 10 marks as the Blues held on to win 11.11 (77) to 9.8 (62) on Friday night at the MCG.

It was "Spud's Game", which honours late Saints great Danny Frawley and raises awareness for mental health advocacy.

Earlier this season, McKay needed three weeks out because of his own mental health issues and he has been open about his struggles.

"A problem shared is a problem halved," McKay told the Seven Network post-game.

"So I think the more we can talk about it, speak to a mate the better.

"Everyone is so supportive and brings so much love so it's really great to be able to have a night like this.

"The more we can speak about it and get around each other and help each other, the world will be a better place."

Fellow key forward Charlie Curnow also kicked three goals in the win and coach Michael Voss said it was crucial that he and McKay are playing together again.

"Charlie and Harry are very important pieces to us. We just haven't had them together for a lot of games," Voss said.

"The more games they play together, I feel like the back of the year, they'll hit some solid form.

"They were really good again."

It was a hard-fought win, with Carlton down to one fit player on the bench late in the second term.

Defender Mitch McGovern is the most seriously hit, going to hospital for a chest issue, while Lachie Cowan has a hamstring injury.

Blake Acres (shoulder) and Nick Haynes (neck) were able to play in the second half.

"It didn't have a lot of brilliance in it. It had some brilliant moments, but it largely took a grind," Voss said.

"Get in the trenches, fight our way out of it, hang in for as long as we possibly could and then just wait for our moments."

The third term was a slow grind, with plenty of stoppages, and Voss said that suited Carlton given their injuries.

"I can't imagine it was too pretty to watch, but ... it was the phase of the game we needed.

"We were happy for the game to go dead for a while."

Tom De Koning, reportedly a trade target for St Kilda at the end of the season, had an entertaining duel with Rowan Marshall.

"They'd both walk away saying they had moments," said Saints coach Ross Lyon.