It became crystal clear by the dawn of October that Xavier Prep and Corona del Sol would be on a collision course for the 2017 6A volleyball title. Nothing has happened since to alter that opinion although there are two matches left before that becomes reality.

Xavier Prep is the top seed and defending champ Corona del Sol is No. 2 as the tournament heads to the quarterfinal round. Xavier took care of No. 16 Mountain Ridge and Corona did the same against No. 15 Skyline in the opening round.

Xavier and Corona accomplished something somewhat unique in the history of big-school volleyball power-rankings. Both navigated the regular season unbeaten,17-0 in power-ranking matches. It happened in 2013 when Horizon and Hamilton finished 17-0. Hamilton reached the final, but fell to Xavier. Xavier upended Horizon in the semis.

Last year the best match of the tournament may have been the semis when Xavier and Corona locked up. Corona won, 3-2, and went on to sweep Mountain Pointe in the final. The year before Xavier eliminated Corona in the quarters, 3-0, and went on to the final where the Gators fell to Desert Vista.

This year Xavier and Corona managed to meet in the NIke Tournament of Champions top bracket on Sept. 30. Xavier won, 2-1. They also played a week later in the Gilbert Invitational with Xavier winning, 2-1. Each set of the latter was a two-point difference. Those are the only losses for Corona. Xavier's losses are to out-of-state teams in invitationals and one in an invitational to Mountain Pointe.

Xavier (37-3) is led by senior outside hitter Lanie Wagner and junior setter Shannon Shields. Sophomore Briana McKnight has been a force as an outside as well. The Gators defense is keyed by senior libero Alana Draper and defensive specialist Ashley Yeung. 

Corona del Sol (38-2) is led by all-around senior Brooke Nuneviller, last year's Gatorade Player of the year. Nuneviller leads the Aztecs in killls (513) and digs (431). Corona has plenty of other weapons -- senior Emma West (225 kills) and sophomore Madelyn Noble (250 kills).Senior setter Abby Meyer has 1,117 assists and 207 digs. 

The short list of teams that could pull off an upset if their game is at a high level -- No. 3 Mountain Pointe (34-7), No. 4 Millennium (32-9) and No. 5 Perry (35-6). Mountain Pointe has seven losses -- three mulit-set defeats to Corona, one sweep at the hands of Xavier and an invitational victory and one loss to Millennium. The Pride are led by setter Gabby Leo, outside hitter Piper Manross, opposite Avery Luoma and libero Anna Morse.

Millennium is one of the best defensive teams around. The Tigers rely on libero Nicole Hoff, setter Alyssa Avitia and defensive specialist Annika Payne have combined for more than 1,300 digs. Perry has dominated often, but matches against other top teams haven't gone as well. The Pumas have two losses to Xavier (both in five sets),  one each to Millennium, Hamilton and Basha. The Pumas finished the regular season with an invitational tourney first-place finish. Perry is led by senior hitters Ryann Davis and Lexi Keith. The Pumas finished the regular season winning an out-of-state invitational and took Xavier to five

No. 6 Hamilton has battled through injuries to key players throughout the season. The Huskies are healthier now, but other than one win over Perry haven't been able to crack, Xavier, Corona del Sol, or Mountain Pointe. Hamilton is led by outside Darian Clark. No. 7 Horizon has losses to Xavier, Corona, Mountain Pointe and Perry. It didn't take any of them to five sets. A late season ACL injury has sidelined standout middle Karen Scanlon. Younger players have picked up the slack, but the opponents left are formidable.Huskies are always scrappy and have good depth. No. 9 Sandra Day O'Connor has struggled getting past the first round at state recently. It's last major run came in 2013. The Eagles ended three years of first-round losses with a win over Basha on Tuesday.

Thursday's quarterfinal matchups, all at 6:30 p.m. - #9 SDO at Xavier Prep; #5 Perry at #4 Millennium; #6 Hamilton at #3 Mountain Pointe and #7 Horizon at #2 Corona del Sol.