Coach K puts on a sideline show during Duke’s win over Wake Forest

Was that Mike Krzyzewski departing from his normally composed demeanor, jumping up and down and -- gasp! -- taking off his jacket?

Why yes, it was.

A cynic would say the Duke coach had to do some coaching Tuesday against Wake Forest, which entered Cameron Indoor Arena with a 2-15 conference record and kept the Blue Devils busy until the very end.

Duke prevailed, 79-71, but it wasn’t without some gymnastics from Krzyzewski, who, sans jacket, showed off his vertical leap and used his arms to exhort the crowd after a late Duke basket.

He joked about it afterward, saying America needed to see the physique of a 69-year-old.

The important part was that the Blue Devils required a push. They don’t quite have the feel of the team that churned out a victory over Wisconsin in last year’s NCAA championship.

Grayson Allen, for all his talents, including a 30-point game Tuesday, keeps causing a national uproar (or at least in ACC country) by tripping opponents on purpose. His most recent one drew a rebuke from the conference and the hint of suspension if it happened again.

The big decision next week for the 17th-ranked Blue Devils isn’t which hotel they’ll stay in for the ACC tournament but whether senior power forward Amile Jefferson should be medically red-shirted after missing most of the season because of a broken foot.

Right about now, they miss Jahlil Okafor and Justice Winslow. Tyus Jones too. All three went in the first round of last year’s NBA draft.

Enter Krzyzewski, who in 2011 set the Division I record for career victories and might need more sideline theatrics to get six wins in the NCAA tournament.

“I’m not in bad shape this time of year. I usually have a little gut but I’m all right,” he said Tuesday, drawing laughs from reporters. “I just wanted to show our team anything, maybe a little sign...that they’ve got to get up.”

It was a better outcome than a surprising loss to Pittsburgh last weekend, yet there needed to be maximum effort Tuesday against a team with such little conference cache these days.

“There’s no excuse for us to be tired,” Allen said. “We’re kids in college and we’re in March.”

Duke forward Brandon Ingram sparked a late surge with a blocked shot on a Wake Forest fastbreak, helping erase a rough six-for-17 shooting night. Ingram, a freshman, is projected to be one of the top two picks in the draft.

For Lakers fans there is extra interest in Ingram because if the lottery balls bounce just right, the Lakers might wind up landing the star forward in the NBA draft in June.

Duke also needs to squeeze what it can from workmanlike center Marshall Plumlee, whose two brothers are in the NBA. Plumlee, a senior, had 13 points and 17 rebounds Tuesday as the tough guy down low.

The slim, trim nearly septuagenarian Krzyzewski has volunteered to help.

“Different teams need different things and as a leader I didn’t have to do that much last year,” he said. “A lot of times it was just telling them ‘Be you,’ or whatever. This group is a lot younger and less talented obviously...but talented. It just needs a little bit more.”