For the University of Hawaii football team, the vacancy sign was illuminated for fewer than 22 hours.

A day after starting center Brenden Urban suffered a knee injury, the Warriors moved quickly to fill the opening in the middle of the offensive line on Thursday. John Wa‘a, a third-year sophomore from Kahuku High, and Asotui Eli, a second-year freshman from Kealakehe High, split the reps in 11-on-11 drills during the second day of training camp.

“We miss Urb, and thank God (the injury) wasn’t serious,” offensive coordinator Don Bailey said of Urban, who is expected back before the Sept. 3 opener against Colorado. “It does give us a chance to experiment a little bit knowing he’s coming back.”

The Warriors turned to Wa‘a, who started two games at guard in 2014, and Eli, who had not played center previously in a game or practice.

Left tackle Ben Clarke, who played center his first two UH seasons, could be summoned, according to line coach Chris Naeole, in a “break-the-glass” emergency.

“But we’ve got guys who can play the position,” Naeole said.

Wa‘a said it was “cool being with the first” unit, but “I still have to work hard. It’s not my spot.”

Naeole praised Wa‘a as a hard worker and experienced blocker. Wa‘a said he often seeks advice from Clarke.

At the end of spring training, Naeole told Eli to work on “snapping” the football.

“Tui is a smart kid,” Naeole said. “He redshirted last year. He can develop. Hey, jobs are open. He has good size. He’s a strong kid. He’s pretty smart.”

At guard or tackle, Eli favored the punch technique of thrusting his open hands onto an opponent’s chest. At center, Eli said, “the hardest part is keeping your feet moving. I like punching, but my feet have to keep moving with the D-linemen. That’s what I work on. You have to have a lot of awareness, too.”

Bailey said Eli displayed the strength and agility to play center.

“We wanted to try to find a spot for him,” Bailey said. “If guys will allow us to get them out of their comfort zone, then who knows what will happen. If they’re willing, they can blossom into really good players.”

Wa‘a was one of the first to commit to UH’s 2013 recruiting class. Eli was an early pledge to the 2014 class, a promise he kept despite growing interest from other schools.

“Hawaii was the first one to offer me,” Eli said. “I had a lot of pride in Hawaii. I already committed here. I wasn’t going to disrespect coach (Norm) Chow or, especially, coach Naeole. If I say I’m going to come here, I’m going to come here.”