Pittsburgh ace A.J. Burnett held the punchless Cardinals to four hits over seven innings and the Pirates rolled to a 7-1 victory Saturday night to move back in front of the tightest division race in baseball.
Lynn (13-9) gave up seven runs and 10 hits in four erratic innings to lose his fourth straight decision.
''I've got to do better than I did tonight,'' he said. ''It was unacceptable. I didn't get the job done. I've got to make better pitches in big situations and not let the big innings happen. I've just got to get better and I will.''
Lynn received little help from the typically potent St. Louis offense. The Cardinals have scored just one run during their three-game losing streak.
''We've had a few balls hit hard, but not a lot,'' manager Mike Matheny said. ''I like what our offense has done over the majority of the season. You don't want to take a couple of games and start making conclusions. We're just going to keep going about it.''
The Cardinals still lead the National League in batting average and runs but are 5-10 against the Pirates this season. Pittsburgh received another jolt early Saturday afternoon when first baseman Justin Morneau was acquired from the Minnesota Twins.
Matheny and Lynn both believe the current slide is nothing more than a hiccup.
''I'm not happy with way I'm throwing the ball, but I'm going to fix it and I'm looking forward to the next month because it's going to be better,'' Lynn said.
It can't get much worse for Lynn after the Pirates jumped on him early.
Pittsburgh went in front 2-0 in the second inning on RBI singles by Burnett and Jose Tabata. Marlon Byrd drove in Pedro Alvarez to spark the third, and Russell Martin followed with a three-run homer to give Burnett all the support he needed.
''You could really feel the momentum shift there,'' Matheny said. ''You don't want that to happen. You want your team to keep grinding, but you could feel things shift. Our guys kept fighting and our bullpen did a great job of holding them, but we never got much going.''
Burnett's command had something to do with it. Mixing in a newly mastered changeup, Burnett (7-9) struck out six and walked one as the Pirates improved to 79-56 and moved within three victories of their first winning season since 1992.
''It's a great feat,'' Burnett said. ''It's been a long time, but our goals have been higher than that.''
That's certainly evident after the Pirates put together their second big trade in five days. Pittsburgh brought in Marlon Byrd and John Buck from the New York Mets on Tuesday.
Byrd homered in his Pirates debut on Wednesday. Morneau won't get a chance until Sunday at the earliest. Manager Clint Hurdle hoped Morneau would be available on Saturday night if needed. Instead, the Pirates were already up by six runs when Morneau popped into the dugout. He spent the next hour joking around with his new teammates.
''You try to get here as quick as you can because you want to be a part of this,'' Morneau said.
Important baseball as the calendar flips to September is an annual rite of summer in St. Louis, but the pitching staff has begun to fray after five months of dominance.
Lynn appeared on his way to a career year after winning his 13th game of the season in a romp over Cincinnati four weeks ago. His ERA over his last four starts is 7.66.
Pittsburgh ranks 10th in the NL in runs scored, one of the main reasons general manager Neal Huntington aggressively pursued Morneau. But the Pirates are averaging 5.2 runs per game during their current six-game homestand, and Morneau's addition gives Pittsburgh another proven bat to join MVP contender Andrew McCutchen and slugging third baseman Pedro Alvarez.
NOTES: Reliever John Axford, acquired on Friday from Milwaukee, pitched a perfect seventh in his Cardinals debut. ... The Pirates have outhomered St. Louis 18-3 in 15 meetings this season. ... St. Louis SS Pete Kozma grounded out while pinch-hitting for Lynn and is hitless in his last 29 at-bats. ... The series concludes Sunday. Joe Kelly (6-3, 2.91 ERA) starts for St. Louis against Kris Johnson (0-1, 3.00). ... The Cardinals have not settled on a starter for Tuesday in Cincinnati. Michael Wacha, Carlos Martinez and Tyler Lyons are all under consideration.
Link to box score: Pittsburgh 7, St. Louis 1
Link to game discussion at The Cardinal Nation message board