With summer officially coming to an end and training camps set to open across the National Hockey League this week, TSN reporters are getting ready for the preseason by looking at the three biggest questions facing each of the seven Canadian franchises.

Kristen Shilton tackles the Toronto Maple Leafs, who finished first in the North Division last season with a 35-14-7 record but blew a 3-1 series lead against the Montreal Canadiens on the way to yet another disappointing first-round playoff exit.

Will Auston Matthews be ready for opening night?

Matthews spent much of last season dealing with a lingering wrist issue, which factored into him sitting out four games. Those absences didn't stop the 23-year-old centre from tallying 41 goals and earning his first Rocket Richard Trophy as the NHL’s leading goal scorer.

Matthews thought allowing the injury to settle down following the Leafs' first-round playoff exit against Montreal in late May would keep him out of the operating room. But as Matthews ramped up his off-season workouts, it became clear his wrist was still an issue. After seeking out a second opinion and some additional imaging, Matthews went under the knife on Aug. 13 to clean things up and hopefully avoid future problems.

The surgery came with a minimum six-week recovery time, and Matthews should be able to remove the splint on his left wrist before the end of September. Even if all goes according to plan, there's no guarantee Matthews will be ready for Toronto's first regular-season game on Oct. 13. The Leafs will open their training camp Wednesday, and while Matthews should be back skating by then, at what point he's able to take contact and feel confident putting power behind his shot remains to be seen.

Toronto won't rush Matthews along in camp, and the team can lean in part on his feedback regarding participation levels in group drills and scrimmages. At this point, Matthews seeing any preseason action appears unlikely. 

If Matthews isn't ready for Game 1, Toronto's depth down the middle would be severely disrupted. John Tavares and Alex Kerfoot would take over in the top six, with Pierre Engvall, Jason Spezza, David Kampf and Adam Brooks all in the mix to fill the bottom two centre spots. 

Who plays left wing on the top two lines?

​The Leafs potentially face questions at centre to start the season, but there's no doubt about their uncertainty on the wing.

Zach Hyman, a top-six stalwart the last five seasons, is gone to Edmonton. Alex Galchenyuk and Joe Thornton, both of whom played throughout the lineup last year, aren't around. So, the Leafs will go into training camp with serious holes to fill on the left side. 

General manager Kyle Dubas brought in several players on short-term contracts over the summer for just that reason. Nick Ritchie (who had 15 goals in 56 games with Boston last year) and Michael Bunting (10 goals in 21 games with Arizona) both project to get long looks for significant jobs with their new teammates. Returning players Wayne Simmonds and Ilya Mikheyev will also be in the mix for top-six roles after playing mostly on the third and fourth lines a season ago. 

William Nylander has been slotted onto the left wing frequently as well, a move that could open the door for off-season signees like Kampf and Ondrej Kase to move into the top-six at right wing if needed. Or there's always a dark-horse candidate like rookie Nick Robertson, who would like nothing more than to push his way into an audition for a major role with the big club. 

​All in all, the possibilities are there for Toronto. The tricky part will be finding the right mix.

How does the goaltending picture shake out?

Jack Campbell had a career year starting for the Leafs last season, posting an NHL-record 11 straight wins to start the year, and finishing 17-3-2 with a .921 save percentage and 2.15 goals-against average.

Numbers like that would have made it easy to anoint Campbell as the starter once again this year, especially since Frederik Andersen departed for Carolina in free agency. But Dubas didn't go out and sign Petr Mrazek to a three-year, $11.4 million contract in July for nothing. There's a competition to come, and both goaltenders should get a crack at assuming the No. 1 role.

After all, the 2020-21 season was Campbell's first time acting as an NHL starter. He'd been a backup for Andersen in Toronto previously and was second behind Jonathan Quick in Los Angeles before that. Campbell hasn't started more than 31 games in any season of his career, leaving question marks over how he would fare as the top guy in this forthcoming 82-game slate. 

Meanwhile, Mrazek has started 40 or more games in four seasons, and produced a save percentage over .900 in all of them. Toronto also made a significant financial commitment to Mrazek. Clearly the Leafs are expecting him to push, and possibly surpass, Campbell. Time will tell who comes out on top.