The news on Morgan Rielly doesn’t appear to be a worst-case-scenario but it certainly isn’t a best-case scenario, either, as he will be placed on LTIR with a knee injury.

After an accidental knee-on-knee collision with Kyle Palmieri in the third period of last night’s 3-2 overtime loss to the Islanders, Rielly will be out for a minimum of 10 games or 24 days. Based on the early reports on the nature of the injury and timeline for recovery, it is an MCL sprain requiring four-to-six weeks to rehabilitate, so it’s not season-ending-level disastrous, but it will likely keep Rielly out until the new year.

Rielly has been a consistently healthy minute-eating presence for the Leafs on the backend for much of his career and had been clocking north of 23 minutes again this season while chipping in 16 points in 20 games, all assists. Needless to say, it’s a major hole to fill.

The next highest point producers on the Leafs blue line are Rasmus Sandin (six points, all assists) and Mark Giordano (four points, one goal), so in addition to his ability to log big minutes and push the play offensively at 5v5, the Leafs’ defense core is significantly lighter on offensive production in his absence.

As much as the scoring depth among the forwards and Auston Matthews’ 5v5 production have been major talking points through 20 games, the slow blue-line production from anyone other than Rielly is a notable piece of the puzzle in regards to the Leafs’ bottom-10 5v5 scoring, so losing their 65+ point producer certainly is not what the doctor ordered here.

Barring an acquisition, injuries to Rielly, TJ Brodie (oblique, experienced a recent setback in recovery), and Jake Muzzin (neck, to be re-evaluated in late February) leave the Leafs forging ahead with Mark Giordano – Justin Holl as their top defense pairing followed by Rasmus Sandin – Timothy Liljegren and Victor Mete/Jordie Benn – Jordie Benn/Mac Hollowell.

Since Brodie was knocked out of the lineup with an oblique injury, Giordano has been averaging 21:23 a game, up from 18 minutes a game prior to Brodie’s injury. Justin Holl is just north of that figure at 21:46. Jordie Benn’s return from injury helped cushion the blow of losing Brodie somewhat as he’s logged 18 minutes a game including nearly two minutes on the penalty kill.

In addition to larger 5v5 responsibilities, Sandin will be leaned on more in power-play duties with Rielly out as Giordano — technically the oldest player in the league — is already seeing a significant uptick in 5v5 and PK ice time.

While weathering the Brodie and Muzzin injuries of late, the Leafs have shown a renewed commitment to their 5v5 defensive play with their five-man structure and the way the forwards have supported the defense. The Leafs have allowed just seven 5v5 goals against in the five games since Brodie went down.

Their resiliency and team defense is going to be tested even further now as all six D, on a blue line that was already stretched thin, are going to need to play higher in the lineup than is ideal and take on even more responsibility. The Leafs’ big guns up front are going to have to show their leadership at a time of significant adversity and dig in deeper both offensively and defensively to get the team through this without tumbling down the standings. Unlike a Boston or New Jersey over in the Metro, the 10-5-5 Leafs have not built themselves much of a cushion inside an Atlantic Division with six teams above .500.

The schedule is not doing them any favours, either, as the Leafs are about to play five games in seven days starting with a visit with the Devils, who are winners of 13 straight and on the verge of a franchise record. It’s a grueling test, but also an opportunity to show the depth of resolve and character in this group.