Kolten Wong made a dazzling defensive stop in the eighth on a hard grounder he nearly turned into an inning-ending double play. Former 41st-round draft pick Kevin Siegrist worked a perfect inning.
Setup man Carlos Martinez recorded one out in the eighth, leaving Rosenthal in a tough bind. Seth Maness gave up the tying single to Nava in the sixth before getting a double-play ball to stop it there.
The end result, though certainly unique with the winning run awarded on an obstruction call, was another win at home where the Cardinals have dominated all year. They have a chance to really take control with Lance Lynn (2-1, 5.40) facing Clay Buchholz (0-0, 5.40) in Game 4 on Sunday night.
They're 6-1 at Busch Stadium in the postseason after going 54-27 during the season, second-best in the majors. They're 70-43 at home in the franchise's postseason history.
Rosenthal struck out the side to save Game 2 in Boston and doesn't need to fret about the blown save. He threw more than an inning 12 times during the regular season, six of the outings scoreless.
Matt Holliday's two-run, tie-breaking double in the seventh put the back end of the bullpen in perfect position. It could have been a larger cushion.
Molina's RBI single in the first gave him a hit in six straight World Series games dating to Game 5 of the '11 Series. Starter Joe Kelly, who allowed two runs on two hits in 51⁄3 innings, has worked at least five innings in all 19 regular-season and postseason starts.
The sellout crowd of 47,432 was the largest for a baseball game at 8-year-old Busch. It's not the largest overall, however, with a soccer friendly matching Chelsea and Manchester City attracting more than 48,000 in May.