The loss snapped Boston's seven-game winning streak. The Bruins are now 21-3-1 since Nov. 1.
Against the Stars, the Bruins were sluggish and undisciplined in the first two periods and fell behind 4-1 before coming alive in the final stanza, but it was too late and Boston suffered its first defeat since a 2-0 loss to the Florida Panthers on Dec. 8 at TD Garden.
Dallas gained an early 1-0 lead after it capitalized on a two-man advantage at 3:21 of the opening period when Loui Eriksson notched his 13th goal of the season. It was the first time in six games that Boston allowed the first goal.
The Bruins knotted the game at 1-1 during a 4-on-4 situation at 11:39 of the first period. Boston's David Krejci gained control of the puck in the offensive zone, moved toward the top of the slot and fired a shot on net that was redirected by Tyler Seguin for his 15th goal of the season.
In the waning minutes of the opening period, the Stars gained a 2-1 advantage when Trevor Daley scored at 16:59.
It didn't stop there.
The Bruins' Zdeno Chara was called for interference and Dallas took advantage of it when former Bruin Michael Ryder gave the Stars a 3-1 lead with a power-play goal at 19:20. The three goals Bruins goaltender Tim Thomas allowed in the first period equaled the most he's allowed in any one game this season.
When it appeared that the second period would be a scoreless frame, the Stars scored at the 19-minute mark. Tom Wandell finished off a 2-on-1 to give Dallas a 4-1 lead.
In the closing seconds of the second, the Bruins began to throw their bodies around and that momentum carried over into the third period.
The Bruins remained on the attack in the final 20 minutes, but the defending Stanley Cup champions couldn't respond from a subpar first 40 minutes and suffered the loss.
PEVERLEY BACK: After missing the previous two games with an undisclosed injury, Bruins forward Rich Peverley returned to the lineup against the Stars. He was back on his line with Benoit Pouliot and Chris Kelly. Peverley also worked on the power-play and penalty-killing units.
LOW RYDER: Ryder faced his former team for the first time Saturday night since leaving Boston via free agency when he signed a two-year deal with the Stars worth $7 million. He posted 18 goals and 23 assists for 41 points in 79 regular-season games during the 2010-2011 season in Boston. In 25 playoff games, he scored eight goals and added nine assists. His biggest play, of course, was during Game 5 of the Eastern Conference quarterfinals when he made a glove save on the Montreal Canadiens' Tomas Plekanec. Ryder is one of only three players to leave Boston after the Bruins won the Cup last spring, joining Tomas Kaberle (free agent) and Mark Recchi (retired). Ryder played a total of 235 games with the Bruins from 2008 to 2011.
UP NEXT: The Bruins will return to Boston after Saturday's game, but will continue their current road trip Wednesday in New Jersey. After that game against the Devils, the Bruins will begin a four-game homestand on Thursday when they host the Calgary Flames. The biggest game of the upcoming homestand, however, will be on Saturday when Boston hosts the Vancouver Canucks in a rematch of the Stanley Cup Finals.