Pujols wound up 4-for-5 with two home runs and St. Louis scored eight runs over the final three innings.
The Mets held a 7-4 lead heading into the top of the eighth, but Pujols' first homer cut into the Cardinals' deficit. St. Louis rallied to tie the game in the ninth against Francisco Rodriguez, who suffered his fourth blown save of the season.
Kyle McClellan (3-2) pitched a scoreless bottom of the ninth but St. Louis went ahead in the 10th with a one-out rally.
Pedro Feliciano (4-4) gave up singles to Rick Ankiel and Julio Lugo and walked Colby Rasmus to load the bases. Sean Green hit Mark DeRosa with his first pitch to tie the game and then Pujols hit his grand slam.
Copyright 2009 by United Press International.