T.J. Clemmings didn’t have time to dwell on what might be wrong with Phil Loadholt.

His veteran mentor had just limped to the sideline and coaches were barking at Clemmings to replace him. The rookie buckled up his helmet, jogged out to the huddle then took over at right tackle for the rest of Saturday night’s opening series.

It wasn’t until the drive ended that he learned the severity of Loadholt’s injury.

“When I came back to the sideline and found out he wasn’t able to go, I was like, ‘All right, you’ve got to step up,’ ” Clemmings said Monday.

With Loadholt lost for the season because of the torn left Achilles’ tendon he suffered against the Tampa Bay Buccaneers, the Vikings will turn to Clemmings, a promising prospect who received Division I scholarship offers for basketball and has played offensive line for only three years.

The Vikings say that before Loadholt’s injury they were pleased with how Clemmings was coming along. But now they have four weeks to ramp up his development to get him as ready as he can be to start against the San Francisco 49ers in Week 1.

And to think, just seven years ago Clemmings was pulling on shoulder pads for the first time.

He was a standout big man on the hardwood with offers to play hoops at Rutgers, Providence and Seton Hall. He wanted to play football, too, but his mother, Fay, wouldn’t let him. Before his junior year of high school, Clemmings asked for permission yet again.

“I figured a ‘no’ was coming,” Clemmings said. “I felt like I had no choice but to give football a try and see what would happen.”

With the help of his dad, Trevor, he finally persuaded mom to let him play the hard-hitting sport.

Foiled by Teddy

Clemmings became hooked on football and quickly blossomed as a defensive end, leading Paterson Catholic High School to an undefeated season and a state title while garnering North Jersey Defensive Player of the Year honors. Scout.com hyped him as the top college recruit in the state.

Clemmings committed to play at Pittsburgh and played on a defensive line that included Aaron Donald, who was named the 2014 NFL Defensive Rookie of the Year in his first season with the St. Louis Rams. Clemmings suited up as a freshman, sat out 2011 as a redshirt, then started six games at defensive end the following year.

In 16 career games at the position, he did not record a sack. The closest he came was to a certain Louisville quarterback named Teddy Bridgewater.

“I have a picture in my locker of me almost getting Teddy,” Clemmings said, bursting into laughter. “I almost had a sack on Teddy. Obviously I wish I could have gotten more and been a better defensive player.”

Before Pittsburgh’s bowl game in 2012, coach Paul Chryst approached him about moving to offense. Clemmings, looking for more playing time, agreed. And maybe, just maybe, if the switch was successful, he might get an NFL tryout someday.

“I was thinking, ‘Man, I’ve got two years.’ That’s just not enough time to become one of the best tackles in the country,” Clemmings said. “I guess I proved myself wrong.”

Indeed. Clemmings started all 26 games at right tackle over his final two collegiate seasons, and in 2014 he was named first-team all-ACC by both the coaches and the media.

Next man up

Clemmings, having displayed the athleticism of a power forward and the tenacity of a defensive end, was touted as a potential first-round draft pick. But due to concerns about an old injury, a stress fracture in his foot, he lasted until the fourth round before the Vikings stopped his fall.

During the spring, the Vikings experimented with playing Clemmings, who is 6-5 and 309 pounds with long arms that can keep pass rushers at bay, at right guard. But that fizzled out quickly. By training camp, he was back at right tackle, where he feels most comfortable.

“He is having an outstanding camp,” offensive coordinator Norv Turner said. “He played well in the Hall of Fame Game. He gets thrown into action earlier in the game than he thought. I thought he played extremely well. He’s a young player with a bright future, and he’s going to have to step it up.”

Clemmings cited Loadholt as one of the veteran linemen who took him under his wing. Loadholt invited the 23-year-old to plop down in the chair next to him in meetings and advised him on what to expect as he transitioned to pro football.

That’s why Clemmings is saddened that his first chance to start in the NFL comes at the expense of his injured teammate.

“I just told him that I’m praying for him and to keep his head up,” he said. “He said that whatever I need, he’s always going to be there for me. Just give him a call.”

Clemmings, who got the first-team reps Monday, feels he is off to “a solid start” in his first few months with the Vikings. He admits that he isn’t ready to be a starter quite yet. But he believes he has enough time between now and Week 1 to do something about that.

“I’d say I feel like I’m getting ready,” he said. “I’m getting there.”