Pitching has been the key to the St. Louis Cardinals successful start this season, but Saturday night the Redbirds pitching faltered and a lack thereof was what led to a 5-3 loss to San Diego.

After falling behind 4-0, the Cardinals rallied to get three runs back, but came up short in front of a sellout crowd of 45,288 fans at Busch Stadium. It was the 16th sellout of the season for St. Louis.

Starting pitcher Lance Lynn (11-5) did not have his A-game from the get-go and failed to make it past the fifth inning.

"He just never had a feeling for his fastball," Cardinals manager Mike Matheny said. "I think the body language is something we need to continue to work on and it wasn't his best showing in that regard either."

Lynn disagreed with his skipper about his fastball.

"My fastball wasn't the problem," Lynn said. "It was the off-speed stuff."

Lynn gave up single runs in the first and second before allowing two more in the third. Over his first three innings of work, Lynn threw 20-plus pitches in each of the first three frames.

"When you look at the runs I gave up, they were tough runs," Lynn said. "I should have been out of the third. And then in the first a ground ball gets through the four-hole and in the second they manufactured one there and that is just part of baseball."

By the end of Lynn's night, he had 91 pitches and just 57 strikes through his five innings. Lynn finished the night allowing four runs, six hits and three walks while striking out just one batter.

Lynn acknowledged he did not get the job done Saturday night.

"A starter going five is not going to get it done." Lynn said.

When he was finally pulled, Kevin Siegrist had thrown 10 pitches and walked the only two batters he faced before being pulled. Seth Maness then came in and threw three straight balls to his first batter before getting the Padres' pinch hitter to fly out to center. Maness then fell behind on the next batter 3-1 before eventually getting a ground out to first. Maness' final batter struck out.

In the three hitters Maness faced in the sixth inning, he did record three outs, but also threw 21 pitches.

Even reliever Randy Choate was affected by a case of throwing outside of the strike zone, falling behind 3-1 before eventually striking out the one batter he faced.

The only St. Louis (58-37) pitcher to have any real success and a low pitch count was Trevor Rosenthal, who retired the side in order in the eighth inning on nine pitches.

Of course, that success did not carry over to the ninth for Rosenthal. After striking out Everth Cabrera on eight pitches, Rosenthal allowed a single to Chase Headley and an RBI double to Carlos Quentin to put San Diego (43-55) up 5-3 before Matheny went to the pen for the fifth time.

The most exciting moment of the game though, had to be when 11-year minor leaguer Brock Peterson came up to bat in a pinch hit role and received a standing ovation from the crowd.

"That was cool," Matheny said. "He will never forget that, there is no question. Just his whole story is really special and how he has persevered through his career and today was a rewarding day just for him to put on this uniform and be out there for the anthem, let alone to get an opportunity to walk on the field and help contribute with us getting real close."

Peterson didn't even realize what was going on.

"I was just trying to stay focused in the moment," Peterson said. "I was just trying to get a pitch that I could handle in the zone."

Peterson got the Cardinals within one run of San Diego when he recorded an RBI groundout in his MLB debut.

Peterson pinch hit for Lynn in the bottom of the fifth and came to the plate with a standing ovation. After working a nine-pitch at bat, the rookie who was just called up, grounded out to shortstop in a play that scored David Freese from third to get the Cardinals within one run at 4-3.

"The guy and what he has been able to do so far this year (in the minors) is very impressive," Matheny said. "Coming up there and putting a good bat together, that is all we ask for a guy coming off the bench."

Peterson walked back to the dugout to another standing ovation from the crowd at Busch Stadium.

"I honestly didn't even notice (the standing ovation)," Peterson said. "I was just kind of happy I got a run in and had productive at bat and helped the team."

In the top of the fourth, Matt Carpenter became the first Redbird to reach base when he walked to open the inning. He moved to second one batter later when Jon Jay singled for St. Louis' first hit of the game.

Both runners moved up 90 feet on a passed ball and then scored on Allen Craig's two-run single.

St. Louis mustered up just four hits in the game. Jay, Freese, Craig, and Daniel Descalso. Jay and Matt Carpenter both reached via free passes.

With the series tied, the Cardinals will look to take the rubber game of the series this afternoon. The Cardinals will send Adam Wainwright to the hill against Eric Stults.