Allen made 26 saves and improved to 4-0-0 career against the Ducks. It was also his career-best 23rd win of the season.
Lehtera’s goal was a product of a strong forecheck by Tarasenko, who forced a turnover behind the Anaheim net. The puck went straight to Jaden Schwartz, and he found Lehtera all alone in front of the net.
Berglund capitalized on a turnover from Ducks defenseman Josh Manson 2:59 into the third.
Rakell pulled the Ducks to within one with an unassisted goal at 15:27.
Tarasenko restored the two-goal advantage at 17:22 and added an empty-netter 66 seconds later.
It was the third straight win at home for the Blues against the Ducks, and St. Louis is 9-2-2 at home against Anaheim since 2010.
Getzlaf put the Ducks up 1-0 with a power-play goal 5:17 into the second. Allen made the initial save on Ryan Kesler, but Getzlaf banged home the rebound as it went off Allen’s shoulder.
Getzlaf’s goal came on a 5-on-3 advantage for the Ducks after the Blues were called for too many men on the ice while already killing off Lehtera’s interference penalty.
Stastny tied the game on a tip from Carl Gunnarsson‘s point shot. The goal snapped a 14-game scoreless stretch for Stastny dating back to Feb. 6.
The Ducks are now winless in their last three games after winning 11 straight.
NOTES: Blues D Gunnarsson signed a three year extension worth $8.7 million before the game. Gunnarsson has seven points in 62 games this season and a plus-6 rating. … Ducks D Sami Vatanen did not play after getting clipped in the chin area during Wednesday’s loss to the Avalanche. He was replaced by D Korbinian Holzer. … Blues F Troy Brouwer played in career game No. 600. … The NHL rescinded the game misconduct penalty called against Blues F Ryan Reaves during a game Wednesday night against Chicago.