LOUISVILLE, Ky. — The top teams in the country begin battling it out for the national championship this Thursday and Friday, as the NCAA Division I Softball Regionals kick off the road to the Women's College World Series in Oklahoma City.

The Eugene (Ore.) Regional starts things off on Thursday and runs through Saturday, while the other 15 Regional sites compete Friday through Sunday.

Florida, the defending national champion, is the No. 1 seed in the 64-team tournament, while Oregon, the top team in the USA Today/NFCA Division I Top 25 Poll and host of the Eugene Regional as the No. 2 seed, takes the No. 1 ranking into the postseason.

Other teams hosting regionals, with their tournament seed in parentheses, are Michigan (3), Auburn (4), LSU (5), Alabama (6), UCLA (7), Tennessee (8), Florida State (9), Missouri (10), Oklahoma (11), Arizona (12), Louisiana-Lafayette (13), Georgia (14), James Madison (15) and Notre Dame (16),

Thirty-two conferences were awarded an automatic qualification, while the remaining 32 slots were filled with at-large selections.

The winners of each of the double-elimination regionals advance to one of eight best-of-three super regionals on May 21-24 for the right to be one of eight teams advancing to the Women's College World Series on May 28-June 3 at ASA Hall of Fame Stadium - OGE Energy Field in Oklahoma City. The remaining two teams after double-elimination bracket play at the Women's College World Series will compete in a best-of-three championship series to determine the 2015 national champion.

Click HERE to see where the teams are playing and for an interactive NCAA tournament bracket. Click HERE to purchase tickets at the various regional sites.