What in the name of Ponce de Leon is Carlos Beltran trying to do?

Acting about two-thirds his age, 36, Beltran apparently happened upon that apocryphal fountain of youth Sunday when he used his legs — and his brain — to beat the Miami Marlins 3-2 before a third straight sellout house (43,741 paid) at Busch Stadium.

Not only did Beltran beat out a rare bunt to fuel a third-inning, two-run rally, but he was credited with a steal of home later in the inning. In the ninth, the 2012-13 Cardinals All-Star starter made a sliding catch in right field on Jeff Mathis’ leadoff blooper, which was just fair.

Discussing his “small ball” offensive plays in the third, Beltran, who leads the club by a wide margin in home runs with 19, said, “That’s how I believe we have to play the game sometimes.

“We cannot depend every day on us hitting home runs, doubles and triples and scoring a lot of runs. Some days, you’ve got to manufacture.”

With the score tied at 1-1, Matt Carpenter was hit by a Jose Fernandez pitch to start the third. Beltran almost never bunts. He has had just one sacrifice bunt in five years and he doesn’t bunt for hits very often, having just one last year.

“I have had a lot of opportunities do that this year,” said Beltran, who pushed this one lefthanded. “I don’t know. You just do it.

“I didn’t really think too much about it,” said Beltran, although he had noted that third baseman Ed Lucas was playing back.

Matt Holliday walked and Allen Craig delivered a sacrifice fly, which moved Beltran to third.

With what happened next, Matheny said the Cardinals were merely trying to stay out of a double play with David Freese at bat and runners at first and third and one out.

“As you all know, we’ve hit into a few,” offered Matheny. The Cardinals, who banged into two more Sunday, lead the National League with 91 double plays grounded into.

Freese struck out on a full-count pitch and Holliday, running off first, then skidded to a halt and got into a rundown.

“He stopped because he had a really bad jump,” said Matheny. “But we’d given him the signal to take off, so he needed to.”

Beltran, who said his legs haven’t given him any trouble since spring training, sized up the matter quickly and dashed for home, sliding perfectly around catcher Mathis, who couldn’t handle first baseman Logan Morrison’s low throw.

“Obviously, (Beltran’s) legs are feeling pretty good,” said Matheny. “It was well executed as far as Carlos’ portion. And Matt did all he could do.

“But, once again, we weren’t trying to steal bases as much as we were trying to stay out of the double play.”

The Cardinals’ major-league low total for steals ballooned to 22 with the two-bag windfall.

Holliday’s steal total swelled to three and Beltran, the only player active in the major leagues with 300-plus homers and 300 steals (Alex Rodriguez is on the disabled list), now has two steals this year.

“I guess I was the difference in the game today,” said Beltran, but without braggadocio.

“When Matt stopped, I know I’ve got to go. He did a great job. He was trying to hang out as much as he could to try to give me an opportunity to take off.

“There’s already two outs so I’ve got to find the perfect moment to try to go home.

“When the ball was tossed to the first baseman, I felt that was the first moment for me to go because he’s a lefty. In order for him to throw, he’s got to make a turn. I knew that was going to give me a little more time to maybe sneak a couple of steps.

“Thank God, I was able to slide — and I made it.”

While Beltran correctly recalled that he had a bunt single last year, he couldn’t remember the last time he stole home. “A long time ago,” he said.

Beltran has played in the majors since 1998 and an admiring Holliday said, “When he’s feeling healthy ... he’s been a top-tier, amazing player. I think the only tough period he’s had when he’s struggled with his knees or whatever. I’m never surprised by watching him play.’’

Equally admiring Craig said, “He’s one of the best players in the game. He showed why today in all facets of the game — defense, offense and baserunning. That was a pretty incredible slide at home to get in there safe. That ended up being a pretty big run.”

In the ninth inning, Craig watched from first base as Beltran chased Mathis’ looper. “He came a long way to get that ball,” said Craig.

“It’s not an easy catch. I think he’s still got it. I haven’t noticed any weakness in his game. He still has his speed. He can throw and hit and do it all.”

Now that the Cardinals have caught up to division-leading Pittsburgh again, they meet up Tuesday with Houston, which beat the Cardinals once in two games a couple of weeks ago in Texas and has the dreaded Bud Norris pitching.

“I know they don’t have the best record in baseball,” said Beltran, “but we’ve got to approach these guys like we’re playing Cincinnati and Pittsburgh. You really have to go out and send a message to them.”

Beltran sent a message of his own on Sunday. Smiling, he inquired, “Who says I’m old?”

Derrick Goold covers the Cardinals and Major League Baseball for The Post-Dispatch. Follow him on Twitter at @dgoold or on Facebook at Facebook.com/BirdLandPD

Rick Hummel is a Cardinals beat writer for the St. Louis Post-Dispatch.