On the verge of falling into utter volleyball frustration, 12th-ranked Hawai'i went "all in" last night and somehow found a way to beat 23rd-ranked Cal Poly.

The Rainbow Wahine (6-4) gritted out an improbable comeback in Game 4 — with freshman Amber Kaufman making her first collegiate appearance — and finally found a way to finish the Mustangs off, 29-31, 27-30, 30-23, 30-28, 15-12.

Hawai'i led the fifth game 14-8 before Cal Poly, for the second night in a row, fought off four match points — three coming from Rainbow errors. The Mustangs beat UH in five games Thursday.

"I'm sure everybody in the arena was taking a deep breath at that point (14-12)," UH coach Dave Shoji said. "It's not easy to close games. Once you get a little tentative, they sense that and they made a couple good plays."

After a UH timeout, Jamie Houston squeezed her 28th kill through two blockers to end it after 2 hours and 40 minutes. She buried her first five swings in the decisive game.

A Stan Sheriff Center crowd of 4,874 was probably torn between bringing the 'Bows back and finding a less agonizing sport to follow when UH was down 19-12 in Game 4. The thought of losing its third in a row and dropping to 5-5 — precisely where it was a year ago — must have energized it.

"I think this was huge," Shoji said. "People were hinting it was a must-win situation. I didn't want to admit to that, but it certainly was important for us to get a split. We're not going to get many more opportunities to play a ranked team, if any. This will go a long way during (NCAA) selection time."

Last year's team was dogged by health problems. This team is drowning in them. Last night Nickie Thomas, who was starting in the middle between injuries, said her right knee is sprained and she will be evaluated further Monday.

Thomas, who missed the first four matches with an ankle injury, hurt her knee Thursday. Tara Hittle, a starting hitter and the 'Bows' primary passer, said this week that she is out for the season with leg and ankle problems.

The loss of Thomas forced Shoji to put Kaufman into the fragile mix. He had planned to red-shirt the freshman, but she is now the only backup in the middle on scholarship. Kaufman came in with UH down, 11-9, in Game 4.

The change changed nothing at first, and while Kaufman's numbers were modest, just the different look, and maybe some of Kaufman's frenetic energy, accomplished something.

The 'Bows scored nine straight with Elise Duggins serving to go ahead 20-19. That game was tied five more times before Sarah Mason buried one of her 14 kills to make it 28-27. Houston tooled another and Kari Gregory and Kanoe Kamana'o roofed Alicia Waller on game point.

Gregory would finish with 10 stuffs. Five Rainbows had double-digit digs, led by libero Jayme Lee, and both left sides and middles buried 10 or more kills.

The Mustangs (7-4), unlike Thursday, were also balanced with four hitters in double-digit kills. But, up two games and closing on its fourth upset of a Top-20 team, Cal Poly's passing broke down.

"Tonight I thought we played good volleyball the first two sets," Mustang coach Jon Stevenson said, "and then it was probably not knowing how to play in that position — up 2-0, playing great volleyball, hitting .325 against a team of Hawai'i's caliber. I'm not sure the girls knew how to handle that situation."

For the first time since the first weekend, against a ranked team, the Rainbow did know how to handle the situation.

"Duggins went on a run and everything started to fall into place," Shoji said.

The 'Bows appeared to have control all the way to 29 in Game 1, despite a series of mental breakdowns.

There was no hint of UH control in Game 2. After 10 ties, Hawai'i fell back 21-18 on consecutive Cal Poly stuffs — it had just three in the first two games. From there, the Mustangs played keepaway with the lead, frustrating UH four times when it had a chance to tie.

Game 3 was just as one-sided, with Hawai'i grabbing all the Mustangs, who hit .067, would give them. The 'Bows, running on desperate energy, began to find some consistency with their passing.

Reach Ann Miller at amiller@honoluluadvertiser.com.