"That was the turning point of the game, I think," Lynn said.
The Cardinals coasted to a 12-3 victory over the Brewers in Game 2 of the National League Championship Series on Monday night at Miller Park.
Lynn was credited with the win on a night the bullpen stepped up in relief of Edwin Jackson, who exited after 4 1/3 innings.
Six St. Louis relievers combined to allow one run on one hit with two walks.
Arthur Rhodes, Lynn, Fernando Salas, Marc Rzepczynski, Mitchell Boggs and Jason Motte came in to help the Cardinals even the series.
As lopsided as the final score was, the Brewers still had hope in the fifth inning, loading the bases with one out while facing a 7-2 deficit.
Jackson opened the door by issuing a four-pitch walk to Corey Hart to open the inning. With one out, Ryan Braun delivered a ground-rule double to center.
Lefty Arthur Rhodes came in to face Prince Fielder, who walked, filling the bases.
Lynn entered to face Weeks, who connected on a two-run homer an inning earlier.
Weeks grounded to shortstop Rafael Furcal, who flipped to second baseman Nick Punto, who made a nice turn and throw. Pujols stretched and secured the ball on a bang-bang play.
TV replays showed Weeks was just safe, but first-base umpire Sam Holbrook ruled him out.
Weeks and Brewers manager Ron Roenicke argued with Holbrook, but the chance of a big inning evaporated.
"Big part in the game, whether he was safe or out," Roenicke said. "You guys saw the replay. That was a big play. If he's safe, we have a run in, and we have an at-bat coming up with [Jerry] Hairston. Big play in the game."
Pujols praised the execution of the curveball thrown by Lynn.
"That was a great pitch," the first baseman said. "That was an inning right there that it could have gone both ways, I think.
"Rickie is a great hitter. And Lance just made a great pitch and we got out of that inning. If they can score there, obviously the game could have changed.
"It was a good pitch, a great turn by Nick and [Furcal], and we were able to get out of that inning with no runs."