DALLAS - The Dallas Stars knew they had to contain Pierre Turgeon, Keith Tkachuk and Scott Young.

But Marty Reasoner? Reasoner, who played nearly as many games this season in the minors as he did the NHL, set up the Blues' first goal and scored the next two as St. Louis beat Dallas 4-2 Friday night in the Western Conference semifinal opener.

I don't think Dallas was too worried about me, said Reasoner, who played in only one of six games in the first round.

That's what the playoffs are all about, said Blues coach Joel Quenneville. Sometimes guys you don't expect end up coming through for you - not that we don't think Marty can do that.

The Stars suffered another loss early in the second period when centre Mike Modano knocked legs with Alexei Gusarov. Modano limped off the ice with an injured left ankle and did not return. He left the arena wearing a walking boot.

An MRI exam Saturday will determine whether Modano, who leads Dallas with three goals and five points this post-season, will be back for Game 2 Sunday night.

He's our best player, Dallas coach Ken Hitchcock said. So it would be as deflating as if St. Louis lost Turgeon.

The Stars were trailing 2-1 when Modano left. Within eight minutes, they were down 4-1.

That was actually an improvement over the way Dallas responded to Modano's last injury. In the first round against Edmonton, the Stars gave up three goals in a shorter span while Modano was getting 35 stitches on his nose.

He's a top player, a big part of their power play and 5-on-5, Quenneville said. It was a break for us knowing he didn't play a majority of the game.

Former Blues star Brett Hull tried leading a comeback, but he was repeatedly snuffed by goalie Roman Turek, who also was facing his former team.

Turek, a backup on Dallas' 1999 Stanley Cup championship squad, made 21 saves - including five on Hull in the third period - to improve to 4-0-2 against the Stars.

They tried hard, but they didn't have a lot of scoring chances, Turek said. I feel good. It's a big confidence boost for us.

Ed Belfour, who has failed to win all six games against his former understudy, had little help in stopping St. Louis' early flurry.

Dallas defenceman Darryl Sydor contributed to the Blues' first two goals and was on the ice for all four St. Louis goals. Captain Derian Hatcher was with him for three of them.

This is one of the worst games we've played in a long time, Hatcher said. We just didn't do a whole lot of things right. We were not ready to play. That's the bottom line.

Reasoner had 35 points in 34 games for Worcester of the American Hockey League. He was recalled three times by St. Louis and had four goals and nine assists in 41 games.

He got rolling early by taking a giveaway by Sydor in the Dallas zone and feeding Pavol Demitra on a 2-on-1 chance. Demitra slid the puck between the pads of Stars goalie Ed Belfour.

After Dallas' John MacLean tied it 53 seconds later, Reasoner stole the puck from Sydor against the boards, walked in on Belfour and beat him on the glove slide for his third career playoff goal.

All the Stars were caught out of position on Reasoner's second goal, allowing him to again skate at the goal untouched.

Turgeon scored on a 3-on-2 break, using a screen from MacLean to beat Belfour.

Brad Lukowich scored Dallas' other goal with 7:38 left.

The Stars then failed on their sixth power play and couldn't score in nearly two minutes with an empty net.

Dallas has not scored on its last 19 tries with the man advantage. Among the chances the Stars wasted in this game was a double-minor against Blues captain Chris Pronger in the opening minutes.

St. Louis has killed all 28 power plays it has faced this post-season.

Notes: The Blues' victory made it a clean sweep for all four road teams in second-round openers. The only other time that happened was 1968. ... Dallas has lost all four second-round series in which it has lost the first game. ... The Blues are trying to get to the conference final for the first time since 1986. They've fallen in the second round eight times, twice to the Stars' franchise - in 1991, when Minnesota went to the final, and in '99, when Dallas won the Cup.