Jacque Jones led off the 10th inning with a double off Cardinals reliever Jason Isringhausen (4-6). Jones moved to third on Angel Pagan's bunt single. Then with bases loaded and one out, Nevin hit a shot over the head of draw-in left fielder Scott Spiezio to end the game.
Trailing 4-3, the Cardinals tied the game in the ninth as Ryan Dempster blew his sixth save of the season. He walked pinch-hitter Jim Edmonds to lead off the inning and then on the next pitch Ronnie Belliard hit an RBI-double to left-center, scoring Edmonds from first, who just beat the tag at the plate.
Dempster then loaded the bases with one out by walking pinch-hitter Timo Perez and Aaron Miles.
Cubs reliever Will Ohman struck out pinch-hitter Juan Encarnacion. Then Michael Wuertz (1-0) came into face Pujols.
Pujols hit a fly ball that Pierre snagged in center with a leaping catch in the ivy to end the inning.
"I knew where I was at, I finally got back on it in time. I just didn't know with the basket, if it was going to hit the basket or not. So you have to go up there thinking it's not going to hit it to make the catch. I think this year I have two or three that hit just right off my glove like that so it felt good to bring one down," Pierre said.
Pujols just nearly missed his fifth career grand slam.
"I told Wuertz, 'You knew how much park to work with, didn't you'. We had a couple of inches left, I think," Nevin said.
Cubs starter Carlos Zambrano, backed up an impressive eight scoreless inning outing against Houston on Monday by allowing two runs and six hits in seven innings. He struck out six and walked two.
"He's not going to give in just because we got to him early. He was being real aggressive with guys," said Chris Duncan.
But Duncan ruined Zambrano's chance of becoming the first 14-game winner in the National League with a solo home run leading off the eighth off Cubs reliever Bob Howry that tied the game 3-3. It was Duncan's 13th of the season.
Nevin blooped a pinch-hit RBI-single off Jorge Sosa in the eighth inning to put the Cubs ahead 4-3.
Yadier Molina and Duncan homered for the Cardinals.
"We gave it an outstanding shot. We had it tied twice. We missed a chance there in the ninth. We just couldn't do quite enough," St. Louis manger Tony La Russa said.
After struggling in the first two innings, Zambrano retired 12 in a row, including striking out the side in the third inning and struck out Pujols on three pitches in the fifth inning.
Cardinals starter Jeff Suppan pitched 4 1/3 innings, allowing three runs and eight hits. He struck out three and walked one.
Molina homered on the first pitch of the second inning off Zambrano. It was Molina's fifth of the season.
- Cardinals SS David Eckstein missed the game with a strained muscle in his left side. He was hurt on Friday after sliding into Cubs catcher Michael Barrett in the third inning. He is day-to-day.
- Edmonds, who has been out with post-concussion syndrome, pinch-hit in the ninth and stayed in the game in center.
- Cubs SS Cesar Izturis did not play because of a tight hamstring.
- After striking out in the fourth inning, Zambrano tried to break his bat over his knee, but failed.
- Barrett had the day off for the Cubs.