DALLAS -- Chris Mason was good -- and had some luck on his side, too.
Mason withstood a 14-shot first period and has allowed four goals in his last four games to improve to 10-3-4 in his past 17 games.
"That was a celebration of exceptional goaltending, that's what it was," Blues coach Andy Murray said.
Rookie T.J. Oshie scored the go-ahead goal in the third period. With the game tied at 1, Oshie skated in from the right side and lifted a sharp-angle shot over goalie Marty Turco's shoulder at 6:50 of the third period.
"We've been climbing (in the standings) and it's been fun to be a part of," Mason said. "Every game means something. There's no team out of it. Every game is a playoff game."
Mason has led the charge for the Blues, playing in his 17th straight game.
"It all started with Mason," Oshie said. "He definitely made a lot of saves that he probably shouldn't make. He's really what kept us in the game until we got our legs under us and started feeling better."
Turco made 19 saves, and Jere Lehtinen had a goal, but Lehtinen missed on two other prime chances for the Stars, who lost their third in a row.
"We didn't score, made mistakes and we have hit more posts the last two games than I can remember," Stars coach Dave Tippett said.
Berglund scored his 17th goal of the season at 8:59 of the third period to extend the Blues' lead to 3-1.
Dallas got off to a fast start when Lehtinen tapped in Mike Ribeiro's centering pass at 6:16 of the opening period. Lehtinen nearly scored again about five minutes later, but was denied by Mason on a breakaway. Lehtinen's shot hit the post with about 13:45 to play.
The Blues tied it at 1 with the help of Turco's puckhanding gaffe. Dallas held a 12-3 shots advantage when Turco's clearing pass landed on the stick of McClement, who scored into an open net at 13:09 of the first period.
The Stars failed to score on six power plays and are 0-for-12 with the man advantage over the last three games.
"It's definitely frustrating," Dallas' Steve Ott said. "You can talk about putting in the work ethic, but you've got to capitalize. You can say you hit posts, but it's not good enough. When you don't score on the power play, you shoot yourself in the foot. You have to score goals on 42 shots."
St. Louis put in a strong defensive effort, blocking 19 shots to six for Dallas.
"Guys are battling so hard for me, blocking shots and making my job easier," Mason said.
Dallas is without two of its top four centers: Brad Richards (broken wrist) and Toby Petersen (broken bone in his foot). With both scheduled to be out for at least a month, the Stars acquired center Steve Begin earlier in the day in a trade with Montreal for seldom-used defenseman Doug Janik.
The 30-year-old Begin, who had six goals and four assists in 42 games for Montreal this season, will join the Stars for Friday's practice and projects as a fourth-line center and penalty killer.
- Dallas C Mike Modano was back after missing the previous game with the flu.
- Turco made his 31st consecutive start, extending his franchise record.
- The Blues have won the first two meetings between the teams by a combined score of 9-2.
- Dallas had been 10-5 in its previous 15 games.
- Blues D Carlo Colaiacovo had to be helped from the ice with 2:39 left in the second period and did not return after getting hit in the ankle by a slap shot. His condition will be evaluated on Friday.