OMAHA, Neb. (AP) — The NCAA baseball tournament opened Thursday with one regional beginning play. The tournament starts in earnest Friday. The 16 regional winners advance to super regionals next week, and the final eight go to the College World Series in Omaha beginning June 17.

No. 1 national seed Oregon State (49-4) has won 16 straight games, including Pac-12 sweeps over California, Oregon and Washington State.

Oregon State owns a nation-leading ERA of 1.84, more than a half-run better than the next closest team. The Beavers are on track to become just the second team in 25 years to have a sub-2.00 ERA. The other was Arkansas (1.89) in 2013. The Beavers' Luke Heimlich (0.81) and Jake Thompson (1.31) are first and third in ERA, and Thompson (12-0) is first in victories.