Yastrzemski hit an RBI single in the seventh inning and a two-run homer in the ninth to tie the game 5-5 and force extra innings.
Thairo Estrada, Wilmer Flores and LaMonte Wade Jr. hit RBI singles in the 10th as the Giants won for the seventh time in nine games
Giants starting pitcher Anthony DeSclafani needed 78 pitches to get nine outs. He allowed five runs on seven hits and a walk in three innings. He did strike out seven
Tommy Edman hit a grand slam for the Cardinals, who lost for the 12th time in 15 games
Cardinals starter Jordan Montgomery allowed three runs on seven hits in 6 1/3 innings. Giovanny Gallegos failed to hold a 5-3 lead in the ninth inning and Steven Matz (0-7) allowed three runs in the 10th inning
The Giants took a 2-0 first-inning lead. Austin Slater led off with an infield single, then Luis Matos singled in his first big league at bat. After Estrada's RBI single, Flores walked and Patrick Bailey hit a run-scoring infield single
The Cardinals surged ahead 4-2 in the second inning on Edman's two-out grand slam. Singles by Nolan Arenado, Dylan Carlson and Paul DeJong set the stage
St. Louis upped its advantage to 5-2 in the third inning. Nolan Gorman walked, moved up on a wild pitch and scored on Jordan Walker's one-out single.
The Giants cut their deficit to 5-3 in the seventh inning on David Villar's double and Yastrzemski's RBI single
San Francisco was down to its last strike in the ninth inning when Yastrzemski hit his tying homer on a 2-2 fastball.
--Field Level Media