"I treat it like any other at-bat," Alvarez said. "Just trying to go up there and compete, and put a good at-bat together. Obviously, if I work the walk, that's an RBI for the team; if I get a hit, even better. I'm just trying to do something to produce for the team."
"That's just bad pitching right there," Lynn said. "You can't give that guy a chance to do anything in the first inning. I just didn't get it done in the first inning, and that cost us the whole game right off the bat."
It was Alvarez's second career grand slam and the Pirates' first since Derek Lee hit one last Sept. 3 against the Cubs. Twelve of Alvarez's 15 homers have come in day games.
Alvarez came to the plate with the bases loaded and two down for the second straight game, and delivered just as he did the first time. With his club down, 5-2, in the fifth on Friday, Alvarez clubbed a bases-clearing double to tie the game at 5. He's batting .340 with 19 RBIs and seven homers in his last 15 games after hitting .170 from May 11-June 14.
"Right now, he's committing to one plan," Pittsburgh manager Clint Hurdle said. "There were a lot of plans, and a lot of lane changes going on early with what he was trying to accomplish offensively.
"Each day, that's been a lightning rod up there with one swing of the bat that's really given us some direction in the ballgame."
Pittsburgh has scored 11 first-inning runs in its past three games, and Saturday's early lead was a weight off starter Jeff Karstens' shoulders.
"They're a very good hitting ball club, and my job was to minimize the damage, and if they're going to score, make it one run, and not two and three runs that I had given up in my last outing," Karstens said. "It let me relax a little bit, but at the same time, I had to focus and make my pitches and keep my team off the field."
Karstens gave his club seven quality innings in his longest outing of the season. It was his second appearance since returning from shoulder and hip issues on Monday, allowing six earned runs over five innings against the Phillies that day. On Saturday, Karstens gave up two runs on four hits while striking out a season-high seven.
Lynn appeared to be tiring in the fifth -- which would be his final inning -- and the Pirates capitalized. Jose Tabata led off the inning with a double and scored on a seeing-eye double down the left-field line by Walker. The Cards had a shift on to the right side of the infield, and Walker poked the ball past David Freese at third.
Barmes narrowly beat out a bases-loaded double-play ball to score Jones from third to make it 6-2.
Lynn threw 109 pitches, a day after Pittsburgh chased Adam Wainwright following 100 pitches over five innings. Hurdle said before Saturday's game that he hoped his hitters could make Lynn work.
The Cardinals scored two off Karstens in the third, with an RBI fielder's choice by Jon Jay and an RBI single by Matt Holliday. But from there, Karstens allowed just three baserunners in his final three innings, none of whom got past first base.
With the temperature in St. Louis hovering in the high 90s, Karstens changed up his pregame routine and warmed up indoors rather than on the field. He said that, combined with good chemistry with catcher Michael McKenry, made the difference as he threw a season-high 95 pitches.
"I can't say enough about McKenry behind the plate," Karstens said. "For me, I'm a little bit behind the hitters right now because I'm coming back off the DL. I haven't really been able to watch a lot of stuff. I kind of gave him an idea of what I wanted to do, and he went home and did some homework of his own. And today when we met, we meshed it together and went from there."
Jared Hughes threw the final 1 1/3 innings, retiring four straight batters for his first career save.
Pittsburgh tied its season high with four straight wins, and on Sunday will look for its first three-game sweep in St. Louis since May 27-29, 1991.