Dallas had gone 10-1-1 over its previous 12 games to put the pressure on Anaheim, but the Stars have only three games left to overtake the Ducks.
"We're still in the race heading into our final three games and our focus is to be playing as well as we can heading into the playoffs," Stars coach Dave Tippett said. "If we do that, the points will take care of themselves."
The Stars, who've clinched a playoff spot, could have captured the division title if they had won their final four games. By finishing with four straight victories, the Stars would have been no worse than tied with the Ducks and would have had more victories, the first tiebreaker. Now Dallas needs help.
"We didn't want this team to keep us from getting home ice and winning the division," Morrow said. "It's definitely disappointing."
The Stars were on a roll with consecutive road wins over the weekend against Western Conference playoff teams Detroit and Nashville. But Dallas failed to maintain that momentum.
"We knew this would be a tough game coming off the emotional high against Nashville and Detroit," Morrow said. "But great teams find a way to win this one. It was a missed opportunity for sure."
With the game tied at 1-1, Metropolit put the Blues in front with his 14th goal from the right circle at 13:44 after a turnover by Stars defenseman Stephane Robidas. Weight's deflection for his 15th of the season at 14:01 extended St. Louis' lead to 3-1.
St. Louis is 5-6-4 in its past 15 games, but the Blues improved to 26-16-9 since Andy Murray took over as coach. St. Louis is 12-9-4 in its past 25 games against teams headed to the playoffs.
"We've got one of the best records in the league over the last 50 games," Murray said. "We've beaten some of the top teams in the league. We're just trying to finish the season strong."
Stempniak skated unimpeded from the right boards and into the circle, where he beat Dallas goaltender Marty Turco with a wrist shot for his 26th goal at 10:46 of the first period to make it 1-0.
Ribeiro tied it at 1-1 with his 18th of the season, taking a cross-ice pass from Morrow and lifting a shot over Sanford, who was sprawled on the ice, at 10:09 of the second period.
After the Blues scored twice in the second, Morrow made it 3-2 on a power play with his 14th goal of the season at 19:45 of the second period, banking a sharp-angle shot off Sanford's pads.
But the Stars couldn't draw even despite a 30-24 shots advantage.
"We needed a better start," Ribeiro said. "If we take the lead, it's a different game. They've been beating us all year. We just need to learn from it."
- Weight had three goals and two assists in the four games against Dallas this season.
- Robidas returned to the Dallas lineup after missing seven games with a concussion.
- The Stars were without D Trevor Daley (upper-body strain), RW Jere Lehtinen (lower body strain), C Eric Lindros (groin), D Darryl Sydor (hand) and RW Matthew Barnaby (concussion).
- Out for the Blues were LW Dallas Drake (wrist), D Jay McKee (hip), D Bryce Salvador (collarbone), G Manny Legace (knee), LW Martin Rucinsky (hip) and RW Vladimir Orszagh (knee).