The Anaheim Ducks stalwart defenceman kicked a puck into his own net and failed to block a centring pass that led to another goal. And then there was the play in which Pronger raised the ire of the Senators, when he hit Dean McAmmond in the head and knocked the Ottawa forward woozy.
Rather than taking a stranglehold of the best-of-seven Stanley Cup finals in Game 3 on Saturday, Anaheim dropped a 5-3 decision and allowed the Senators to cut the Ducks series lead to 2-1 with Game 4 at Ottawa on Monday.
It wasn't all Pronger's fault, but he was certainly in the middle of too many difference-making plays in a game in which the Ducks squandered three one-goal leads. The biggest one came with 1:26 left in the second period. Guarding the front of the net, Pronger's foot was in the wrong place on McAmmond's go-ahead goal.
McAmmond gave Ottawa a 4-3 lead when his centring pass from the end boards, banked in off the skate of Pronger, who watched helplessly as the puck dribbled in behind goalie Jean-Sebastien Giguere.
Pronger also allowed Antoine Vermette to sneak a pass through his legs, setting up Anton Volchenkov's one-timer from the left circle that sealed the victory eight minutes into the third.
The Senators won't forget Pronger's hit on McAmmond 2:03 into the third period. McAmmond had just gotten a shot off from the slot, and was skating past Pronger when he appeared to stumble. Pronger then struck McAmmond across the cheek with a forearm, sending the player to the ice and into the end boards.
McAmmond was knocked cold and required assistance to leave the ice.
Pronger was not penalized on the play.
The loss ended the Ducks five-game win streak and marked only the second time they've dropped a game when scoring the opening goal this post-season.
It was an uncharacteristic performance for what had been a determined Ducks team that showed few flaws - out-hitting and out-hustling the Senators - to win the first two games of the series.
After limiting the Senators to 36 shots in the first two games, the Ducks allowed 29 on Saturday.