The NCAA softball tournament regionals opened Friday with two mercy-rule victories, including defending champion Oklahoma's rout of Prairie View A&M in the Norman regional. 

The Sooners, who have won 35 games this season by run rule, secured their first victory in the tournament with a combined no-hitter by sophomore pitcher Nicole May and senior Hope Trautwein. 

Women's Softball Championship Oklahoma Sooners

The Oklahoma Sooners logo in the dirt during a game between the Oklahoma Sooners and the Florida St. Seminoles during the Division I women’s softball championship at ASA Hall of Fame Stadium June 10, 2021, in Oklahoma City.  (C. Morgan Engel/NCAA Photos via Getty Images)

Oklahoma collected 11 hits and four homers to win its first tournament game with hopes of defending its Women’s College World Series title next month in Oklahoma City. 

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Entering the tournament in 2021 as the top-seeded team, the Sooners earned their fifth national title after defeating the Florida State Seminoles, 5-1. 

Oklahoma Sooners softball champions

The Oklahoma Sooners celebrate after defeating the Florida St. Seminoles during the Division I women’s softball championship at ASA Hall of Fame Stadium June 10, 2021, in Oklahoma City. (Morgan Engel/NCAA Photos via Getty Images)

Seeking their first national championship, the Oklahoma State Cowgirls earned their own run-rule victory over the Fordham Rams with a 12-0 win to open the Stillwater regional. 

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The five-inning shutout was Oklahoma State’s 16th of the season, and the 12-run margin was the second-largest in NCAA postseason play, according to the team’s website. 

2021 NCAA Division I Women's Softball Championship

A view of the field before a game between the Oklahoma Sooners and the Florida St. Seminoles during the Division I women’s softball championship at ASA Hall of Fame Stadium June 10, 2021, in Oklahoma City.  (C. Morgan Engel/NCAA Photos via Getty Images)

A total of 64 teams are competing this weekend for 16 spots in the super regionals. Only half of those teams will advance to the Women’s College World Series next month.

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The UCLA Bruins and Tennesse Lady Vols also opened their regional tournaments with a pair of run-rule victories, allowing just one run apiece.