The Maple Leafs are getting an early test of their depth.

After losing centre Scott Laughton with a pre-season foot injury, another member of their fourth line grinders was hurt Saturday, which proved a turning point in a 6-3 road loss at Detroit.

After taking a 2-0 lead, coach Craig Berube was pre-occupied slapping together new lines after left winger Steven Lorentz exited in the first period with a suspected head injury.

Meanwhile, Detroit’s three-goal middle period underlined the break-out trouble Leafs have had with their new personnel, from exhibition action through the first two live-fire exercises.

The consequences included some very tired defencemen. Morgan Rielly and Brandon Carlo were forced into separate two minute-plus shifts on the long bench change in that period. Max Domi briefly tied the game in the third, but Detroit went ahead on the evening’s only power-play goal, by Lucas Raymond, who had two goals while Patrick Kane added a goal and two assists. Simon Edvinsson and Andrew Copp added empty netters.

After Detroit coach Todd McLellan was critical of his team’s flat home opener, its best snipers — Kane, Dylan Larkin and Marco Kasper — all had clean looks to beat Anthony Stolarz. The Leaf netminder had to make 20 saves before the game was half complete.

Toronto’s fourth line had led the way in a strong first period forecheck, before Lorentz was rattled in a collision with Detroit’s Ben Chiarot.

Right winger Calle Jarnkrok, whose play has kept Easton Cowan from making his NHL debut on the fourth group, finished directing Nicolas Roy’s shot over the red line, Jarnkrok’s second in as many games.

The changes, post-Lorentz, included William Nylander going to the top line in the final period with Auston Matthews and Matthew Knies. Nylander was already moved down from his second unit to replace Lorentz with Roy and Jarnkrok.

The latter duo drove the net with Roy breaking his stick blade getting a piece of Rielly’s point shot. Multiple points for Jarnkrok, Roy and Rielly after four periods weren’t on many peoples’ bingo cards.

Matthews snapped one off of the bar moments later that just missed banking in, and after shooting wide on Toronto’s first power play, negated the advantage with an errant high stick. The power play as a whole has been slow, while Matthews is stuck on one empty net goal with Toronto’s record now 1-1.

Berube said Saturday morning that much of the decision to sit Cowan a second time was not wanting to break up a winning lineup from Wednesday against Montreal. With Saturday’s clunker and pending Lorentz’s status, it’s now which home game Berube lets Cowan into, Monday afternoon’s rematch against the Wings or Tuesday versus Nashville.

Winger Sammy Blais has also yet to play his first game since being claimed on waivers on Monday.

lhornby@postmedia.com

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