Given the disparity in the standings with the bottom of the Atlantic Division, the third Bruins-Maple Leafs contest of 2017-18 earned itself a billing of a potential first-round preview. In any event, Saturday marked a show-me game for both teams.

In front of a Hockey Night in Canada audience and 17,565 on Causeway St., the Bruins showed the Leafs what they’re all about.

Without Brad Marchand and Noel Acciari — and with a returning Charlie McAvoy — the Black and Gold snapped a six-game skid against their Original Six rivals and earned a 4-1 victory.

Here is what we learned as the Bruins extend their lead on the Leafs to five points — with four games in hand.

McAvoy doesn’t miss a beat

Twelve days ago, McAvoy was at Mass General Hospital undergoing a heart procedure to treat an abnormal heartbeat. He had a couple of hiccups, but for the most part, McAvoy didn’t miss a beat.

Back at his usual spot with Zdeno Chara on the top defensive unit, McAvoy kept pace in 18:51 of ice time.

“He still gave us some quality minutes, made good plays, but you could tell obviously that he had been out a little while,” head coach Bruce Cassidy said about McAvoy’s first game in two weeks. “Obviously, the other guys picked him up when they needed to, but he still made his plays and was a good player for us.”

It wasn’t the most eventful return for McAvoy as he deflected Mitch Marner’s power-play tally past Tuukka Rask, but McAvoy wasn’t shy pursuing the puck while staying physically engaged.

Rask went over to McAvoy after that first-period hiccup, a gesture that the former Boston University standout surely appreciated.

“Yeah, I mean, he’s a great teammate. He’s an unbelievable teammate and an unbelievable player,” McAvoy said about Rask. “I’m kind of feeling a little upset there, obviously it’s a bounce you can’t really control, but to have him come and tap me on the pads there and say ‘hey, no worries, it’s fine,’ that meant a lot to me as far as focusing and getting back into the game.”

Chara adds another historic milestone

1,400 games and counting — and he’s not stopping anytime soon.

Whether he was killing penalties, disrupting the shooting lane or helping in the transition game, Chara once again provided a big presence in securing a pivotal Bruins victory.

His workmanlike approach on this night resulted in 24 minutes of ice time — including 5:06 shorthanded time on ice — one assist, five hits, two shots on goal and a plus-2 rating.

“I said it in the room too, that in our business, you are obviously measured by wins and losses, but those moments when you have those highs and lows, that’s when you really rely on your teammates to support you and give you the special, special push and energy,” Chara said about the milestone. “Over the course of 20-plus years, I’ve been very lucky that I had really good teammates that I could always rely on, and this group is very special.”

Indeed, Chara and the Bruins put together a special performance against a quality Maple Leafs bunch.

Bruins D layers up

Chara and McAvoy weren’t the only Bruins defensemen who made an impact Saturday night.

From obstructing the neutral zone to keeping the Leafs in the perimeter in their attacking end of the ice, all six blue-liners and Tuukka Rask had their layers on display Saturday night.

Even with the chances that the Leafs got in the prime scoring areas, Rask was there to make the timely save. None was more timely than robbing Tyler Bozak with a highlight-reel stick save on Toronto’s second power-play attempt to keep things tied at 1-1.

“I actually had a pretty good basis on that like I waited for the puck to get there and then dove, I made good timing it just hit my blade,” Rask said about his save on Bozak, one of 23 of the night. “Skill and luck I guess.”

Rask and company needed that skill and luck against a red-hot Leafs squad.

In their two games before coming to Boston, the Leafs outscored the Rangers and Islanders by a 9-0 aggregate. If it wasn’t for a little bit of puck luck, they would’ve been on the other end of a shutout against the Bruins, who are 25-5-4 since being swept by Toronto back in November.

Bruins top line — without Marchand — holds Matthews trio in check

Even without their leading scorer, the Bruins top line finds a way to shut down some of the league’s marquee players. Matthews found that out first hand against Danton Heinen, Patrice Bergeron and David Pastrnak.

Bergeron (at 4:29 of the first period) and Pastrnak (a power play tally at 9:22 of the second) netted their 22nd and 21st goals of the season, respectively, while Heinen tallied two assists. On the other end, they held the Leafs top line of Matthews, William Nylander and Zach Hyman to one, yes one, shot on goal.

“You know, they’re a good line. They’re good on transition, they’re moving their feet well. You
know, they want to make plays, but I thought we did some good things,” Bergeron said about the Leafs top line. “We, for the most part, tried to keep them to the outside. You know, they’re going to have some looks, going to have some chances, but you know they’re good players so I thought our line was moving our feet well and we were on the puck for the most part and we had some good looks as well.”

Barring injuries, Marchand will rejoin his fellow linemates when the two teams meet again on Feb. 24. They may meet again in April.

If Saturday was any indication, the Bergeron line would undoubtedly have the advantage come Round 1.