Mason was not heavily tested in earning his 14th career shutout as the injury-depleted Blues outworked Chicago and limited the Blackhawks' chances.
"In order for us to be successful, we have to work very hard and we did that tonight," Mason said. "We did a great job in our zone, did a great job on the penalty kill and did what it took tonight.
"They let me see the shots, cleared the rebounds, were tough in front of the net, they were tough in the corners, they cleared the puck. We just battled hard and we're starting the see the results."
The Blues have the fewest points in the Western Conference -- and seven players on injured reserve, including forwards Paul Kariya and Andy McDonald, and defenseman Eric Brewer and Erik Johnson. On Wednesday night, they made up for it with consistent effort and close checking.
"Tonight I thought we played smart, took their space away," St. Louis coach Andy Murray said. "We wanted to come into this building (the United Center), which has a great deal of energy, and wanted to suck it up."
Cristobal Huet made 27 saves for Chicago, shut out at home -- and before a 23rd sellout crowd in 23 games this season -- for the first time since March 12, 2008. The Blackhawks have lost two straight games at United Center in regulation to drop to 14-4-5 at home.
Mason made one of his few tough saves just 2:45 into the first, stopping Andrew Ladd from the edge of the crease. The goalie needed to be alert during goalmouth scrums a few times in the second and third, but Chicago generated little sustained pressure.
The Blackhawks entered the game averaging 3.45 goals, but have scored just five in their last four. After going 10-1-1 in December, they're 5-5-1 in January.
"We didn't come out playing the way we should have for consecutive nights," Chicago captain Jonathan Toews said. "We know what kind of team we are, we showed it in December. We want to keep going down that path."
On Wednesday, the Blackhawks were clearly detoured.
"We're disappointed with tonight's effort," Chicago coach Joel Quenneveille said. "You can use a lot of different words to describe tonight's game. Bad would be one."
"I think we're getting sick and tired of people telling us how good we are instead of how hard we worked," he added. "I think that's what's going to get us out of it."
Thanks to three power-play chances -- including a five-minute advantage set up by a major penalty to Chicago's Cam Barker for a hit on David Backes -- the Blues outshot the Blackhawks 16-3 in the first period. However, they led only 1-0 after 20 minutes.
The Blues didn't beat Huet until Woywitka scored a power-play goal on their 16th shot with 1:55 left in the first. Woywitka's drive from the point slid over Huet's left pad and into the net.
Following a scoreless second, Chicago's Matt Walker poked a rebound of his own shot under Mason and into the net at 2:46 of the third. The goal was not allowed, however, because one of the referees had whistled the play dead when Mason covered the original shot with his pad.
Tkachuk made it 2-0 during a 4-on-4 at 7:28 of the third. From the edge of the crease, he stuffed a shot between Huet's pads.
- Blackhawks RW Kris Versteeg, the NHL's rookie scoring leader, suffered an undislcosed injury in the second period of the game and didn't return for the third. Quenneville said he didn't think the condition was serious.
- Chicago D Duncan Keith sat out his fourth game with a probable concussion. Keith, who leads the Blackhawks with just under 26 minutes of ice time per game, may return following the All-Star break according to Quenneville.
- The Blackhawks honored former RW Tony Amonte in a pregame ceremony. Amonte spent nine of 16 NHL seasons with Chicago.
- St. Louis D Roman Polack missed his second game with a broken foot and LW Yan Stastny missed his fifth with thumb injury. They're the most recent additions to the Blues' IR list.