The Eastern Conference-leading Boston Bruins play another Atlantic Division rival for the first time this season when they conclude a two-game road trip against the Buffalo Sabres on Tuesday night.

Even after being bolstered by defenseman Charlie McAvoy's return from his four-game, NHL-issued suspension and Pavel Zacha scoring 36 seconds in, the Bruins suffered their second straight blemish against a divisional foe with Saturday's 3-2 overtime loss at Montreal.

Although the loss was only Boston's second in seven games (5-1-1), the effort led to a hard skate at Monday's practice.

"Energy, focus, we made mental and physical mistakes," Boston coach Jim Montgomery said when asked what was lacking against the Canadiens. "Our execution was not what we've become accustomed to."

Brad Marchand led the Bruins with a goal and an assist, and Jeremy Swayman made several key stops among his 24 despite ultimately taking his first loss (6-0-1).

"I think we're a team that needs to get two points almost every night," Swayman said. "So, a lot of learning (from Saturday). Going to the third with a lead, you want to close that out. So, I want to have a couple more saves there and it's just not good enough."

As Boston continues a true goalie rotation, Linus Ullmark is in line to take the net on Tuesday.

The Bruins will need to give it a better 60-minute effort going forward, especially as a stretch of seven games in 13 days begins when Montreal makes a return visit to Boston on Saturday. The points will soon be coming faster.

"Our schedule has been a little unorthodox (with) a lot of spacing between games," Montgomery said. "Last year, the spacing was time to rest. This year, we haven't had as many 3-in-4s so far. ... After this week, we'll start to ramp it up."

Tuesday will be a milestone night for Sabres captain Kyle Okposo, who is set to become the 46th active player to reach 1,000 career games.

"It's a special day for everybody that helped me get to this point, for sure," Okposo said. "For my family and the people behind the scenes that supported me throughout the whole way."

The Sabres were shut out for the first time this season in Saturday's 4-0 loss at Pittsburgh, playing without a key forward in Alex Tuch (upper-body), who head coach Don Granato said looks to be on target to return Friday at Winnipeg.

With Tuch's injury and Matt Savoie being returned to juniors prior to Saturday's game, Mattias Samuelsson played as a seventh defenseman after being activated from injured reserve.

No matter who's in and who's out, Granato is hoping to see a simpler game from the Sabres as they face one of the NHL's top teams.

"Simplifying. It's easy to say, a little more challenging to execute that," Granato said on Saturday. "I thought we could have executed things a little bit more simple, more direct and when a puck is getting to the net, get there, get more traffic there. ... There were moments we did, but not consistently enough. You don't score, you don't win."

Goalies Ukko-Pekka Luukkonen and Devon Levi have alternated starts over Buffalo's last five games.

If that trend holds, Levi would play his first career game against Boston, the team he shared a city with while playing at Northeastern University. Levi won the last two Mike Richter Awards as the top goalie in college hockey.

--Field Level Media