Oklahoma State Coach Patty Gasso noticed something strange before sophomore Ella Parker launched a towering three-round stroll home run to beat Tennessee 4-3 on Thursday afternoon on Day 1 of the Women’s College World Series.

Gaso looked up and watched as a group of fans left the American Softball Hall of Fame Stadium at the bottom of the seventh inning.

Oklahoma, the second-ranked Oklahoma State, has only three games, from Careen to Do-or-Die knockouts, and Gasso also makes sure her players see it too.

“I shared that with the team,” Gaso said. “It’s not about anything, it’s about people thinking we’re done. One thing, if you’re watching us all season, we’re never going to do it.”

Before Oklahoma's comeback, teams entering the bottom of the WCWS' seventh innings have fallen behind the seventh inning since 2000, according to ESPN Research.

In the first six innings, Lady Vols' right-hander Karlyn Pickens suffocated, and four-time defending champion Sooners (51-7) won the first round between the SEC heavyweights.

Parker's Blast - Her Second Game - dating Oklahoma with Texas No. 6 (3 ET, ABC). Lady Vols (45-16) previously won three best series from the Sooners in March and now faces a knockout match in Florida on Friday night (7 p.m. ET, ESPN2).

"Obviously, it's a gut," Tennessee coach Karen Weekly said. "'I think our team has done a great job. Be proud of the way we play. We don't have time to feel bad for ourselves. We have to prepare for tomorrow's game, and that's what we just talked about in the locker room."

Parker thrived a quiet pitcher-versus-duel dug-off between Pickens and Oklahoma ace Sam Landry, who gave up a run and threw a career-high 139 pitches in seven innings.

Ms. Walls led 3-1 when freshman middle-fielder Amayah Dodge beat the wrong shot at the top of third place.

Tennessee then incorporated a great pitching performance into the late stage. Pickens is a national first team, navigating his own way in a series of jams, allowing three hits, and hitting 7 to 6 innings at the same time. Her only flaw so far is Parker’s first home run.

Pickens sent a lead walk to OU's Alaina Agbayani to open the bottom of the seventh inning. Three batsmen, Kasidi Pickering's two-inning singles put Parker's hero on the table.

Similar to her head coach, Parker was watching the crowd before the clutch.

Parker said after the game that before she entered the batsman's box, she scanned her teammates for the third home run dugout and the former Oklahoma player behind, eventually locking in the history of Class I college softball history Jocelyn Alo.

Seconds later, Parker scored a 0-1 pitch from Pickens and hit an ALO-style shot on the central field wall, which gave the Sooners a fifth walking victory in WCWS history.

"I just think of getting all these players to look up - either in my canoe or leaning against the front fence," Parker said. "And I think I looked at Joss' last bat and I was like: 'We get it...we got it.'"

Parker's game-winning explosion continued her playoff power surge.

Parker was hampered by a lingering foot injury, and from March 2 to April 4, Parker scored five of 42 goals in 42 before regaining the form in the final week of the regular season. Including her two home runs, including two on Thursday, Parker’s nine home runs have been around for all Class I bats during that time since April 26.

"This is a young lady who is still in pain," Gaso said. "She did make a psychological twist in the way she showed it for the team. ... She kept dealing with it like someone I didn't see. It was really hard for her. But again, she really said from the bottom of her heart: it's for the team."

As Oklahoma chases unprecedented five games this spring, Parker carved the latest heroes into the program’s record and probably set the tone for another title.

"As long as we have one swing, we have life," Gaso said.