Buehrle was tagged for five runs in 2 1/3 innings, allowing six hits and walking two. He threw 70 pitches against what could be the Cardinals' opening day lineup.
"That's where I wanted to get," Buehrle said of his pitch count, "but not in 2 1/3 innings."
"The ball was moving too much. I was falling behind in the count. Pretty much everything you're not supposed to do, I did," the left-hander said.
Buehrle signed a four-year, $58 million contract in December to add depth to the Marlins' rotation. He has a 9.95 ERA in two big league exhibitions.
"That's a typical Buehrle spring training," said Marlins manager Ozzie Guillen, who knows Buehrle from their years together with the Chicago White Sox from 2004-11.
"I'm not worried about him. He knows what he's doing. I've seen him for so many years. As long as he is on the mound healthy (when the season starts), because you're going to see some ugly games when he's pitching in spring training. And it wasn't that ugly. 5-0? That was pretty good."
Buehrle allowed eight earned runs in five starts last spring with the White Sox before going on to post a 13-9 record with a 3.59 ERA.
Buehrle also batted Friday for the first time since June 29. He struck out looking with the bases loaded on a 3-2 pitch to end the second.
"It was a little awkward. But it was good to see some live pitching," said Buehrle, who is 5-for-47 (.106) in his career as a hitter.
"We've seen a machine out here and it's throwing at 60 miles an hour. It's a little different than facing live pitching coming in there at 90."
Cardinals starter Jake Westbrook tossed four shutout innings, allowing two hits and striking out four.
Matt Holliday hit his first home run of the spring and is batting .500 in exhibition play.
St. Louis first baseman Lance Berkman returned to action for the first time since Sunday and doubled. He'd been out with a sore left knee.
Marlins RF Giancarlo Stanton said an MRI exam revealed swelling on his left knee. He said he wasn't sure what caused the problem. Stanton hopes to return to action next week. He hasn't played since March 11 when he left the game after being hit on the left wrist with a pitch. ... Cardinals bullpen coach Dyer Miller has left the team to be with family after his brother was killed in an accident. Cal Eldred will be fill in as bullpen coach. ... Cardinals ace Chris Carpenter has thrown off a mound for the first time in nearly two weeks. He had been limited in workouts since March 3 because of a stiff neck. "It was a little better than I had hoped," he said. "I felt good. I felt strong. I'm just happy." Carpenter threw 30 fastballs at about 75 percent of his usual strength after reporting no neck trouble following consecutive days of throwing on flat ground. If he feels well Saturday, he could try to throw off the mound again Sunday or Monday, and pitch batting practice. The Cardinals think they might have a better idea next week of when Carpenter would be ready for exhibition games.