A change to Georgia Tech’s starting lineup didn’t have much to do with an 81-73 win over Southern Tuesday night in McCamish Pavilion, and the Yellow Jackets had better make other changes soon.

Junior center Ben Lammers, who averaged 2.8 points over his first two seasons, put up 19 to easily surpass his previous career high of 10 for the fourth time in as many games as the Jackets built a 40-20 halftime lead, but Tech (3-1) was dominated in the second half.

The Bearkats (2-2) scored 53 points after intermission on 52.6 percent shooting (10-of-38) and outrebounded teh bigger Jackets 20-10 in that time.

Twice in the final minute, Sam Houston State pulled within seven points.

That made it hard for new head coach Josh Pastner to get excited that fifth-year senior Corey Heyward dropped a career-high 10 points in a rare start (for Abdoulaye Gueye), or that Lammers added eight more rebounds and six blocked shots to extend his astonishing early-season start.

“I told our guys before the game, in college basketball, it’s about energy,” Pastner said. “The team with more energy for 40 minutes will win. We were more energized for 20.”

Lammers scored 12 in the first half, and when the Jackets went on a 17-0 run to build a 28-9 lead, he scored nine points, grabbed four rebounds and registered three of his six blocked as Sam Houston State had no size to match him.

No less interesting, Tech made 5-of-8 3-point shots before intermission to at least temporarily mask a problem from the first three games. The Jackets were just 10-of-35 from distance before Tuesday.

Heyward started in place of redshirt sophomore Abdoulaye Gueye, and tied his career high of five rebounds and contributed three assists.

The Jackets shot 60 percent in the second half, but Sam Houston State took 18 more shots thanks largely to the Bearkats’ big rebounding advantage. The visitors also made 6-of-13 3-pointeres after a 1-of-10 showing in the first half.

Senior Quinton Stephens contributed 10 points and 10 rebounds for Tech, but he didn’t need to be told what happened after halftime.

“I think it was a little stale,” he said. “We have to take it upon ourselves to set the standard; it’s just a mindset.”

Overall, Tech was buoyed by a 40-34 edge in points in the paint, but Sam Houston State outworked the Jackets in the second half.

Pastner wasn’t happy about the second half, when the Bearkats pulled within eight points a couple times over the first 10 minutes, and twice came as close as seven in the final 90 seconds or so.

John Dewey, III, scored eight of his team-high 15 points in the first half for Sam Houston State, but his teammates made just shot 5-of-23 in that time, including 1-of-10 from beyond the arc. The Bearkats were out-rebounded 21-15 before halftime.

Then, “In the second half, we didn’t guard,” Pastner said. “You have to give credit to Sam Houston State, but we stopped guarding like we did in the first half and that’s the big difference there.”

Tadric Jackson scored 15 off the bench for the Jackets, yet the visitors twice were within seven points in the final minute, given extra life as the Jackets struggled at the free throw line on the way to a 21-of-36 night from the charity stripe. Jackson made just 3-of-8, and freshman Justin Moore was 1-of-4.

Sam Houston, on the other hand, made but 10-of-18.

“It’s not every year that you have an opportunity to beat a major school,” said SHSU head coach Jason Hooten. “Having an opportunity like this and letting it slip away, I’m hoping we can learn from it.”

Gueye did play, adding two points and two rebounds in six minutes of action.

When the Jackets next play, senior point guard Josh Heath will be eligible for Saturday’s home game against Tulane for the first time this season after serving a four-game suspension for violating team rules.