KATY, Texas -- Stephen F. Austin left the Southland Conference tournament with a bad taste last year.

The Lumberjacks made sure it didn't happen twice in a row.

Thomas Walkup had 19 points and Stephen F. Austin used a big second half run to defeat Sam Houston State 68-49 Saturday and earn its first trip to the NCAA tournament since 2009.

SFA lost 68-66 to Northwestern State in the Southland Conference tournament championship game last year.

"We couldn't let this opportunity slip away because the feeling last year we had leaving out of this place wasn't a good feeling," SFA gurd Desmond Haymon said. "We didn't want to leave here two years in a row feeling the same way.

"The focus the team had stayed there the whole night. The defensive intensity in the second half was there.

Deshaunt Walker added 12 points, and Jacob Parker had 10 points and 12 rebounds for the Lumberjacks (31-2), who won their 28th straight game.

"This is just about everything coming together," Walkup said of the winning streak. "We go out to the court every single day and work hard. It is just a tribute to that. It's just being who we are and coming out every single night with intensity."

The Lumberjacks shot 49 percent from the field and hit 12 of 17 from the free throw line. They controlled the boards, outrebounding Sam Houston State 35-23 -- which led to an 18-5 advantage in second-chance points.

Terrance Motley had nine points, and Will Bond and James Thomas each had eight for Sam Houston State (23-10), which finished shooting 39 percent but struggled in the second half.

The Bearkats have not reached the NCAA tournament since 2010.

"It just wasn't our night, and you have to give them (SFA) credit because a lot of that was due to them," Sam Houston State coach Jason Hooten said. "They played defense really, really well. I thought early in the game we got some good shots that just didn't go in. We executed early. It happens sometimes when you don't make shots, you get frustrated, and I thought we carried that on to the defensive end."

Leading by three, SFA used a 21-5 run over an 11-minute stretch of the second half to push its lead to 56-37. Connor Brooks' layup capped the surge with 7:07 remaining. Parker had six points to lead the run for the Lumberjacks.

During the run, the Bearkats were shot 2 for 8 and turned the ball over six times. Sam Houston State got no closer than 14 the rest of the way.

SFA coach Brad Underwood credited his team's defense for the decisive run.

"Most of it was based on our ability to guard and handle the ball screens," Underwood said. "We did a good change of changing and altering shots at the rim. The one thing I was most impressed with was we did it without fouling. ... We guarded, we used our bodies and did a great job rotating."

Hooten said the Bearkats could not get anything going in the second half, and it snowballed from there.

"They frustrated us," Sam Houston State guard Kaheem Ransom said. "I guess that was clear. We didn't take good shots in the second half, and it showed. They were getting easy layups. It just hurts."

Sam Houston State narrowed the gap to 35-32 on a Ransom 3-pointer less than 2 minutes into the second half.

Sam Houston State scored six straight points to open up an 18-12 lead on Bond's 3-pointer with 8:47 left in the first half.

The Lumberjacks responded with a 14-2 run to grab a 31-24 lead on Desmond Haymon's layup with 3:17 to go in the half. Walker had back-to-back 3-pointers to lead the run for SFA. SFA held a 33-28 lead at the half.