South Florida posted the biggest upset on the first day of the NCAA baseball tournament. The Bulls knocked off the Florida Gators as the bottom seed in the Gainesville Regional. Four of the seven No. 3 regional seeds that played early Friday also won. Arkansas and Texas won their openers in the double-elimination regionals. They are the top two national seeds. No. 3 national seed Tennessee got a ninth-inning grand slam from Drew Gilbert to post a 9-8 walk-off win over No. 4 regional seed Wright State.