Scientists say perpetual motion is impossible, but it's obvious the wheels never stop turning in the head of Bruins coach Claude Julien. His team is 14-1 since Thanksgiving and leads the NHL with a plus-55 goal differential but he's found something not to like about the Boston Bruins team that drew into a tie Sunday for the NHL points lead with the San Jose Sharks.

You'd hate to see what he'd do to his lineup during a losing streak after the coach shook up his lines following his team's eighth-straight victory Sunday, a surprisingly tight 2-1 win over the Thrashers in Atlanta. Julien dropped first-line left winger Milan Lucic onto the third line and promoted P.J. Axelsson to play with center Marc Savard and right winger Phil Kessel. Lucic went pointless in his previous two games, after an eight-game scoring streak. He had the game winner two nights before his mini-slump

Julien also wasn't pleased with his third line of Stephane Yelle centering right winger Chuck Kobasew and Axelsson, cutting their ice time by an average of over three minutes against the Thrashers. Kobasew had 5 goals and 8 assists and was plus-10 entering December, but had only 1 goal and 2 assists and was minus-3 since then before Tuesday night's 5-3 win in Pittsburgh. Yelle had 2 December goals and no assists and Axelsson had 1 goal, 4 assists and was minus-1 for the month.

"Right now those two lines have not been up to snuff in the coaches' view," Julien said Monday. "We just felt a little bit of a change might give both those lines a little spark. I guess it's just preventing things from getting stale, let's put it that way. Guys can get comfortable in situations."

Julien didn't let anyone, not even Michael Ryder, get comfortable in a 75-minute, off-day practice prior to the home-and-home series with the Penguins. Pittsburgh visits Boston Thursday night.

Ryder had the game winner in the Bruins' weekend wins over Atlanta and Carolina and in three of the past four victories. He has 14 goals and 12 assists this season for 26 points and is plus-15. Ryder has 9 goals and 2 assists in December. He has an NHL-best seven game-winning goals this season.

Julien was Ryder's big booster when the Bruins signed the left winger to a three-year contract on July 1. Julien had coached Ryder with the Montreal Canadiens and the Hull Olympiques in juniors, including the 1999-00 QMJHL season when Ryder had 50 goals and 58 assists. Ryder had 25 goals as a rookie the year before the work stoppage, came back and had two seasons of 30 goals. But he slipped to 14 goals last season and was in coach Guy Carbonneau's doghouse for his weak defensive play.

Ryder has been playing with center David Krejci, who has points in 17 of the past 18 games, and Blake Wheeler, who had 2 goals in the win Saturday over the Hurricanes. They were the Bruins' best line in December.

Julien has another tough coaching situation approaching: How do you tell players that helped you to a 14-1 record over the previous five weeks to take a seat? The Bruins' No. 2 and No. 3 defensemen, Aaron Ward and Andrew Ference, will soon be returning after leg injuries. Ference has been out since Nov. 14 and is due to return in early January. Ward has been out since Dec. 2 and is practicing with defensive partner Zdeno Chara.

Meanwhile, center Patrice Bergeron continues to have headaches since his concussion Dec. 20 against the Hurricanes. There is no timetable for his return.

Back-to-back hats -- The Montreal Canadiens remained solidly in second place in the Northeast Division and within distant range of the Bruins by winning five of their past six games and gaining a point in an overtime loss with the Hurricanes. Yet, the Canadiens remain an enigma.

While the Canadiens' expected top scorers, Alex Kovalev, Saku Koivu, Alex Tanguay, Chris Higgins and Guillaume Latendresse continue to struggle, the Canadiens are getting sufficient scoring from the rest of the lineup to rank fourth in the NHL with a 1.24-1 scoring ratio. They are 11th with 2.46 goals-per-game, partly thanks to climbing from next-to-last to 24th in power-play scoring.

They were greatly encouraged Saturday by left winger Alexei Kostitsyn's hat trick in his return from a leg injury. Kostitsyn had all three goals in Montreal's 3-2 win over the Penguins. That was followed Monday by Maxim Lapierre's hat trick in a 5-2 victory over the Florida Panthers.

It was the first NHL hat trick for both players and the 12th time since 1926-27 that the Canadiens scored hat tricks in back-to-back games.

Kostitsyn hadn't had a point since Dec. 4 but he scored at 1:15 of the first period against Pittsburgh and again with a second left in the period, both goals off assists from Tomas Plekanec, who hadn't had a point since Dec. 2. Emboldened, Kostitsyn forced a third-period turnover and five-holed Marc-Andre Fleury for his third goal.

"We've been telling Andrei for months that he has to shoot the puck," Carbonneau said. "He has one of the best, if not the best shot, on the team and you saw that tonight."

Lapierre got his first goal when he collected his own rebound off Florida's Craig Anderson, skated behind the net and scored on a wraparound backhander. Latendresse utilized his shot in the second period by blocking a shot, collecting the loose puck, dropping a pass for Lapierre and then screening Anderson. Carbonneau put Lapierre out with Florida's net empty near the end of the game and he stole a puck at his blue line and scored.

Hold that lead -- The Sabres are having trouble holding leads this season. Only five teams have worse records when scoring first than Buffalo's 11-5 and only three teams have blown more second-intermission leads than Buffalo. Only seven teams have had more trouble holding onto first-period leads.

The problem got worse last week as the Sabres coughed up third-period leads in losses to the Canadiens and Penguins. They salvaged a shootout victory over the Islanders after giving up the tying goal with less than two seconds remaining.

"It's something where we have to figure it out," said Sabres center Paul Gaustad. "We have to make sure we get those points. We can't be where we were last year, a few points out the playoffs and letting points slip away. That's something we'll address in this locker room now, and it's something that can't go ignored. We're taking it very seriously."

Gaustad missed five games and that wNHas a factor in Buffalo's late-game slippage. He's a big body who wears out opponents and he's excellent defensively. Shutting down top centers is his job.

The Sabres continue to miss defenseman Craig Rivet, their big off-season acquisition who came over in a trade with the San Jose Sharks in early July. Rivet has played in only 21 games this season. He missed five games in November after knee surgery and has been out since Dec. 1 with shoulder problems. His return is getting closer. Previously, the Sabres said they were observing him in two-week blocs. Now, they say he is "day-to-day."

Last chance for Joseph? -- Toronto Maple Leafs coach Ron Wilson announced Curtis Joseph will start two games this week, beating Atlanta, 4-3 Tuesday, and against Buffalo Thursday.

The win against the Thrashers was the 450th of his career, but the classy Joseph remains dissatisfied with his game.

Joseph was 0-4-1 with a 4.12 goals-against average this season before the Atlanta game, which comes one week after Justin Pogge, the Leafs' first pick in the 2004 Entry Draft, backstopped Toronto to a 6-2 victory over the Thrashers.

"It just hasn't worked out, you know what I mean?" Joseph said prior to the Atlanta game. "There have been no lay-up games, either, but you have to find that edge. You’ve got to be the difference maker in the game. My first few starts were pretty good, the last two weren't. But I'm not going to base my career on those last two."

Neither will we. Joseph always will be remembered for his class, his community involvement and for ranking fourth to only Patrick Roy, Martin Brodeur and Ed Belfour in NHL victories whenever he chooses to retire.

Quotable -- "We need everybody. This is a team thing. Right now, we're obviously in a tough, tough situation. This is the time to find out about a lot of people." -- Ottawa Senators first-year coach Craig Hartsburg.

News and Notes -- South Buffalo native Tim Kennedy made his NHL debut Saturday night in the 4-3 shootout victory over the New York Islanders. ... He had one shot and two scoring chances, one of which drew a penalty. ... Sabres center Tim Connolly is not close to returning from his rib injury, the team said. ... The Senators lost the first three games of an eight-game road trip, giving them 12-straight road losses. ... Ottawa's 3-11-2 record is worst in the NHL. ... Their 29 road goals are also last among NHL teams. ... Boston’s eight-game winning streak is its longest since an 8-0 run March 30-April 14, 1993. ... Only four of the Bruins’ 13 games this month were on home ice. ... Maple Leafs center Matt Stajan may have surpassed Joe Sakic for weirdest injury this season. Sakic injured his hand repairing a snow blower a few weeks ago. Stajan was hit in the eye by a soccer ball during a pre-game warmup before Sunday's game at Washington. He is expected to miss at least a week. The players were performing a routine exercise but were in a smaller than usual space with balls ricocheting off walls. Stajan said he never saw the ball before he was hit. ... Ottawa rookie Ilja Zubov briefly played on a line with Dany Heatley and Jason Spezza in the 3-0 loss at Vancouver.