Next man up? Try next middle up.

For the Hawaii volleyball team, the injury to senior Annie Mitchem means that her roommate, sophomore Casey Castillo, has the opportunity to start in her place.

The circumstances are not how Castillo — who played sparingly in 19 matches last season — wanted to break into the lineup.

“I’m super bummed for her,” Castillo said of Mitchem, who fractured her left pinkie finger at the end of Tuesday’s practice. “I really feel for her, it’s an unfortunate injury.

“I want to contribute however I can. It’s going to be a transition but I’ve played it before, am familiar with it, but it’s a matter of getting that synergy and connection with our setters.”

Castillo practiced at several positions last season, including middle. She’s been most comfortable as a left-side hitter but can also back up Nikki Taylor at opposite. The 6-foot-3 utility player now can concentrate on one position.

“Annie’s a tough loss, she was our most physical player after summer, but I don’t expect us to lose anything with Casey in there,” associate coach Jeff Hall said. “It’s the ‘next man up’ mantra. She’s got to learn to be up quicker, block a little better. Blocking middle is one of the hardest things to do in volleyball but she’ll get more reps to get her ready.”

Castillo is excited about the chance.

“It’s an amazing opportunity to contribute,” she said. “We have very high expectations for this season.

“It all starts internally. We have to work on our own stuff but also team chemistry and work ethic, focus on what we can control.”

Hawaii, ranked No. 6 in the AVCA preseason poll, opens the season Aug. 26 against No. 4 Wisconsin. Hall, who is in charge while head coach Dave Shoji is at the Rio Olympics, said the team has progressed after the first five days of practice.

“All the kids have gone hard,” he said. “I think we got 2 percent better this week. The goal is to be 2 percent better every day.”

Hall’s observations by position:

Setters (senior Tayler Higgins, juniors Kendra Koelsch and Faith Ma’afala, freshman Norene Iosia). “All four can set really well and run our offense. We have tried to pick up the tempo, go faster, and all have done a really good job doing that.”

Defensive specialists (senior Katiana Ponce, juniors Savanah Kahakai, Clare-Marie Anderson, and Gianna Guinasso, freshmen Emma Smith, Rika Okino and McKenna Ross). “We have an army of them but they’re all really good. The effort on defense has been phenomenal. Savanah is our best libero. She is at another level and is one of the best in the country.”

Outside hitters (senior Nikki Taylor, junior Kalei Greeley, sophomore McKenna Granato and freshmen Kirsten Sibley). “They’re all doing a good job hitting with pace and range. Nikki’s our returning All-American, Kalei is coming off of surgery, Granato is way ahead of where she left off and Sibley has been a nice addition.”

Middles (senior Annie Mitchem, junior Emily Maglio, sophomore Casey Castillo and redshirt freshman Natasha Burns). Blocking has been really good, I’d grade it a B, and it will get better when we spend more time on it. We don’t have enough healthy people yet.”

Burns, who fractured her hand last season and redshirted, has not been cleared to practice. She is expected to be cleared as early as this morning’s practice.

Mitchem is scheduled to have surgery Tuesday and have a pin inserted. The projected timeline is 3-4 weeks to get back in the gym.

“It’s her non-hitting hand so that’s a big difference from last year,” Hall said. “But we will be cautious.”

NOTE: Anderson has been named a UH Presidential Scholar and will receive two years of tuition waivers plus a monetary award. The academic all-Big West selection carries a 4.0 GPA as a pre-med major.