Freshman Jackson Johnson was 3-for-18 on the season before Tulane coach David Pierce inserted him into the second spot of the batting order Saturday.

Talk about your unlikely sparkplug.

Johnson matched his season total with three huge hits, including his first career home run, as the Green Wave bounced back from a drubbing Friday night to beat South Florida 5-3 at Turchin Stadium.

Tulane (30-19, 10-10 American Athletic Conference), which had scored one run in its previous three games combined, evened the series with the Bulls (30-20-1, 11-9) and set up a critical deciding game Sunday between two NCAA tournament bubble teams.

“It was awesome,” said Johnson, who watched from the dugout Friday as Tulane lost 12-0. “I was glad to get out there and give our team a chance to win on Saturday and get the series to tomorrow.”

Johnson’s single in the third inning moved Stephen Alemais to third, allowing him to score on Lex Kaplan’s sacrifice fly to put Tulane ahead 2-1. Johnson led off the sixth with another single before Tyler Wilson hit a mammoth two-run home run into the net behind left field, giving the Wave the lead for good, 4-3.

Johnson then capped of his magical day with a solo shot to right field off reliever Brandon Lawson in the eighth, padding Tulane’s advantage.

“Honestly, I haven’t hit a home run since Cooperstown when I was 12,” Johnson said. “In BP, they always give me crap for it — but his fastball had some arm-side runs, so I backed off the plate about an extra-half inch and tried to get the barrel out there.”

He did not even know he would be in the lineup until he arrived at the stadium after taking a microeconomics final exam in the morning. Regardless of how he performed there, he aced his second test.

“He’s very competitive,” Pierce said. “What I love about Jackson is that he’s got a lot of confidence in himself and he’s been swinging the bat really well (in practice). I talked to him about a week ago and said, ‘You’re a perfect type of guy to be a spark plug for us when we need it.’ Boy, he was awesome today and we needed it.”

The metrics did not favor the Wave winning on a day when starting pitcher Alex Massey and reliever Patrick Duester (6-5) combined to walk 10 batters. Tulane also ran itself into a double play on what appeared to be a perfect sacrifice bunt in the first inning and made two throwing errors on the same play after fielding a bunt in the fifth, leading to two Bulls runs.

The two homers provided the difference. Wilson’s blast, a no-doubter off USF starter Ryan Valdes (5-2), was the starting point. He had struck out on three consecutive changeup pitches in his previous at-bat but got all of another changeup this time.

“Last night, we didn’t get timely hits,” Wilson said. “Today was different, and that played a huge role in the win. It’s just awesome to be the guy to do it.”

Before Saturday, the Wave had a total of two home runs in AAC play.

“We were fortunate,” Pierce said. “But the key to the entire game was that we really just scratched and clawed and we gave ourselves a chance, even though at times we looked pretty ugly.”

Ian Gibaut faced the minimum six batters over the final two innings to earn his seventh save, erasing the only base runner with Tulane’s third double play. Pierce said Gibaut would be available for two more innings in Sunday’s critical finale, with Emerson Gibbs starting as Tulane continues its push for its first NCAA regional bid in seven years.

“There’s so many implications of what happens after tomorrow’s game,” Pierce said. “It’s not the end, by any means, but it (a win) sure positions us a lot better.”