PORT ST. LUCIE, Fla. — Weeks ago, when Adam Wainwright first lined up against Johan Santana for the latter’s debut as a New York Met, the Cardinals righthanded bemoaned his chance to face the lefty and Cy Young winner as a hitter.

He wanted to see the changeup. Not swing at it. Just see it.

Get a feel for it. Watch from the best angle possible how Santana sells it.

On Saturday, Wainwright did more than just watch it.

The Cardinals’ acting ace — and just dispense with the foolishness and call him the opening day starter – nearly turned two Santana changeups into two base hits as the Cardinals defeated the Mets, 10-3, at Tradition Field. Wainwright cracked one changeup down the third-base line and nearly beat David Wright’s back-footed throw to first. In the fourth inning, Wainwright extended a rally with a single up the middle — off the changeup. Afterward, Wainwright said it’s not just hitting against a bona fide ace like Santana that energizes him, it’s pitching opposite him.

“I wish I could pitch against a No. 1 everyday,” Wainwright said. ”I feel like I’m going to beat them sometimes. I feel like they’re going to pitch great game sosmetimes. I thrive off that. Feed off that. I love it. That’s the game’s ultimate competition when you’re going against the game’s best, and he’s proven he is.”

Wainwright threw 67 pitches and held the Mets to two hits — including a solo home run – during five innings of work Saturday. The righthander earned plaudits from manager Tony La Russa and Dave Duncan, who echoed a similar sentiment.

He did what a quality pitcher does.

Threw strikes. Got ahead in the count. Kept the ball down. Closed out hitters.

“Outstanding,” La Russa said.

Since recovering his mechanics from a few difficult outings early this spring, Wainwright has been able to accomplish one of his goals for spring. He didn’t want to add pitches to his quiver so much as add ways to use his pitches. After recent starts, he’s stressed that he’s trying to make all of his pitches work in new parts of the strike zone and to sell them better.

During his last start, against Atlanta, Wainwright felt that in the first inning the hitters could tell a pitch was going to be a ball out of his hand.

He wants more deception. Every pitch should look like a strike — until it isn’t.

On Saturday, he had his best changeup yet of spring, and he used it to freeze Wright in the first inning. He struck out Carlos Delgado in the second inning and got the requisite groundouts to push on through the third inning. Of his 67 pitches, 44 were strikes. He felt most of them looked like strikes coming out of his hand.

It’s the key, after all, to Santana’s changeup.

One of the best pitches in the game, Santana’s changeup thrives of its deception. It comes from the same arm slot, at the same arm speed and with the same everything as his fastball. (Check out this New York Times article on the pitch from earlier in the spring.) Seeing it first hand only reinforces the elements of its effectiveness. Wainwright is looking for that kind of masking for his pitches.

He also should pay attention to his catcher, like, oh, back in that NLCS thingy.

In the fifth inning, Wainwright worked a couple fastballs by Mets catcher Raul Casanova. Catcher Yadier Molina wanted a slider down. Wainwright thought better and tried to bend a curve by Casanova. It wasn’t a bad curve, but it had a bad result — it landed somewhere out past right field for the only earned run Wainwright allowed.

He has two more starts this spring and his goal from them is simple.

“Build. Build. Build,” he said.

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Amazing what speed can do: A day after Brendan Ryan’s wheeled in from second on a wild pitch that scored two deciding runs in a win against LA, Brian Barton got his third triple of the spring and he nearly set up earlier scoring jag by the Cardinals with a dash. In the first inning, Barton reached on an error. When Albert Pujols drove a double, Barton spun around the bases and headed for home. The Mets fumbled the relay, but the throw went to the plate — allowing Pujols to take third. He was there with one out, only to have Santana K consecutive teammates.

Still, speed thrills.

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A clarification on two earlier notes: Brad Thompson will start Wednesday’s game. … Juan Gonzalez’s MRI are being viewed by a specialist before the Cardinals will have a final diagnosis on the abdominal injury that’s kept him off the field and severly complicated the former MVP’s comeback attempt.

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