PORT ST. LUCIE, Fla. — In his first game against major-league competition on Wednesday, Mets prospect Tim Tebow found the learning curve for a 29-year-old rookie isn’t only about trying to hit the curve.

Tebow, the former Heisman Trophy-winning and NFL quarterback, went 0-for-3 with two strikeouts and a hit by pitch (and was immediately doubled off first on a line drive) in the Mets’ 8-7 victory over the Red Sox at First Data Field.

Tebow day in the batter’s box was about what you’d expect from a guy who had never faced a major-league pitcher and started with Rick Porcello, the reigning AL Cy Young Award winner.

It was Tebow’s day getting to the batter’s box that was a problem. Before his first at-bat, leading off the bottom of the third, the lefthanded hitter wandered over from the Mets’ third-base dugout all the way to Boston’s first-base side of the field.

“I didn’t know where he was going,” Mets manager Terry Collins said. “I thought he was going to go shake hands with [Red Sox coach] Gary DiSarcina . . . The umpire told him he had to go back to the other side.”

Said Tebow: “I kind of thought, ‘You walk around because you’re a lefthander.’ I found out you don’t do that.”

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Tebow learned a lot of lessons. He learned umpires sometimes call strikes on pitches you don’t like, such as the 1-and-2 fastball from Porcello that plate umpire Ryan Addition said caught the outside corner. That ended Tebow’s first at-bat. All four pitches from Porcello were 90 miles per hour or better.

Tebow learned when you get a good pitch, you better hit it. In his second at-bat, in the fourth inning with the bases loaded and no outs against righthander Noe Ramirez, Tebow fouled off a hittable fastball.

“Oh, I wanted it,” Tebow said. “There’s no question about it. I felt really good about that swing.”

Later in the at-bat, Tebow put the ball in play for the only time when he hit a sharp grounder to second that was turned into a run-scoring 4-6-3 double play. He received a standing ovation from the crowd of 6,538 as he trotted back to the dugout.

Tebow, 29, hit eighth as the designated hitter. The 6-3, 255-pounder wore uniform number 97 — typical for a low minor-leaguer — instead of his usual No. 15.

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Earlier on Wednesday, Tebow wore No. 15 during batting practice. He hit several home runs off Mets bullpen catcher Dave Racaniello, including one off the scoreboard.

His third time up in the game, Tebow was hit on the right shoulder by a fastball from lefthander Brian Johnson, who like Tebow is a Florida University product.

“Where’s the love?” Tebow said. “No, it’s fine. I’ve been good at taking hits most of my career.”

Tebow theatrically flung the bat away before trotting to first base. He wasn’t there long.

L.J. Mazzilli hit a line drive to second and Tebow was doubled off first. A big baseball no-no. Tebow did not slide back into the base, another no-no.

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“He’s so far behind on the nuances of the game,” said Mets outfielder Jay Bruce. “It’s not like he’s been wasting time. He’s obviously been doing other worthwhile things.”

Bruce and Curtis Granderson could be seen counseling Tebow before and during the game.

“Really ball talk, to be honest with you,” Bruce said. “It was pretty much a normal day at the office.”

It was not. Most minor leaguers didn’t raise $2 million for charity five days earlier, as Tebow did at his golf tournament over the weekend.

His final time up, Tebow looked at three breaking pitches from righthander Brandon Workman. The last one was a beautiful curveball for strike three.

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Tebow said he came into the day thinking about being disciplined at the plate. When he next faces big-league pitching on Friday against the Astros, Tebow said he’s going to try to be more aggressive.

“I think I learned a lot of things,” Tebow said. “Just getting in there, seeing pitches for the first time. First time competing. Felt like I put some good swings [on] when I swung. Didn’t necessarily think some of those were strikes . . . You just learn.”

Collins seemed to indicate Tebow’s appearance on Friday, when he is scheduled to play leftfield, might be his last one in big-league camp for a while. The clock is ticking on Tebow’s quest to reach the major leagues after taking a decade off from baseball. He needs at-bats, and not against big leaguers.

“What he’s attempting to do, not a lot of guys would even try it,” Collins said. “I salute the fact that he’s giving it his best . . . This guy, he’s got a clue. He knows what’s going on.”

Even if he doesn’t always know where to go.