CLEMSON, S.C. -- After Clemson missed the NCAA Tournament, coach Oliver Purnell gave his players a choice -- stay disappointed or move ahead in the NIT.
The Tigers chose to move on.
Rivers finished with 17 points and 14 rebounds, and Booker had 11 points and 11 rebounds.
Purnell watched the NCAA Tournament selection show Sunday and shared the same disappointment as his players when the Tigers, who began the season 17-0, didn't get in.
He worried the past two days whether he and his staff had done enough to motivate the Tigers.
Turns out they had.
"This gives us a chance to move forward," Purnell said.
But it took more than three-quarters of the game before the Tigers gained control.
"I think we're into it now," Rivers said. "Everybody got a little flow."
"It's not the big dance," Rivers added. "But it's the National Invitation Tournament. It's a strong tournament."
The Tigers (22-10) have won the past seven NIT games played at Littlejohn Coliseum.
As the South region's No. 1 seed, they'll get a chance to keep that string going as they'll host Mississippi in a second-round matchup Monday night.
Without Rivers' shooting and Booker's inside strength down the stretch, it might have been ETSU moving on.
Eryk Thomas made an inside bucket that put the Bucs (24-10) ahead 49-48 with 6:22 left.
Cliff Hammonds' 3-pointer regained the lead for Clemson and then Booker, the Tigers' 6-foot-7 freshman took over.
He made two foul shots, then followed with two more inside baskets as Clemson went ahead 57-51.
The Bucs got no closer than four points the rest of the way.
Despite the win, Rivers wasn't certain the Tigers would bring the same fire they had at the end to their next game.
"It depends how we look at it after tomorrow," Rivers said. "Whether we take the next step or whether we just go down in that one."
Courtney Pigram, the Atlantic Sun Conference's player of the year, led ETSU with 25 points.
The Bucs couldn't match up under the boards with the bigger, quicker Tigers, getting outrebounded 51 to 32.
"We knew if we'd give them two, three and four shots, we'd be in trouble," ETSU coach Murry Bartow said. "That's what happened."
Clemson's poor shooting -- it finished 37.9 percent (25 of 66) -- kept things close.
Rivers is Clemson's most consistent outside shooter, but finished 1-for-7 behind the arc. He did his best work under the glass with his career high in rebounds. His previous best was 10 rebounds set a game ago in an Atlantic Coast Conference tournament loss to Florida State.
Clemson started out 17-0 and was the nation's last Division I unbeaten. Things unraveled for the Tigers during Atlantic Coast Conference season, when they lost 10 of their final 14 games heading into the NIT.
Purnell held out hope for an NCAA Tournament berth but had to settle for an NIT top seed and convince his players there was something worth playing for.
The Tigers started quickly and looked like they had control after a 10-0 run gave them a 17-8 lead. But they made only one of their next 15 shots as the Bucs moved ahead 21-19 on Andrew Reed's inside basket with 4:58 left in the period.
A.J. Tyler, a rarely used reserve, sparked Clemson down the stretch in another 10-0 run. He hit a 3-pointer, then followed Booker's miss with a putback. By the time Rivers stroked a 3-pointer 20 seconds later, Clemson was in front, 29-21.
James Mays, the Tigers' second leading scorer, thinks they've put the NCAA disappointment behind them, especially the way they performed when it counted.
"After this win, we're very enthused," Mays said. "Because the competition's only going to get better."