When Oklahoma scores first, it’s incredibly tough to beat.

The Sooners jumped on Oregon early Friday night at Marita Hynes Field in their NCAA Tournament opener, riding D.J. Mathis’ arm for a 6-0 victory and advancing to the Norman Regional’s winner’s bracket game today at 1 p.m. against Arkansas.

OU (44-12) improved to 36-3 when getting on the board before its opponent, something that makes things easier on Mathis, who pitched her 21st complete game of the year.

This time the Sooners led off with three straight singles from Amber Flores, Krystle Huey and Susan Ogden. A fielder’s choice from Samantha Ricketts and a run-scoring single from Lindsey Vandever put OU up 2-0 at the end of the first inning.

“It’s nice, especially coming in the first game of the regional tournament and jumping right out to a two-run lead,” Mathis said. “You can’t ask for anything more as a pitcher.”

Mathis finished the night with six strikeouts and two walks while scattering three hits. She only forced the Ducks into 1-2-3 innings in the first and sixth, but never really struggled despite allowing back-to-back singles to start the seventh.

“I thought we came out attacking,” OU coach Patty Gasso said. “Amber had a great presence at the plate and set the tone for us in all her at-bats. Sam clutched up and D.J. was her regular self and really set a tone for us also off the mound. I loved the way we swung the bats.”

OU had trouble getting anything going after that first inning, as they left six runners on base, until the fifth.

Flores walked to start things off, Huey reached on a fielder’s choice and Ogden singled to center field to give the Sooners runners on first and second with one out.

That’s when Ricketts came through again, bringing Huey around to score with a single to left field. Pinch runner Dani Dobbs then scored on a wild pitch and Iver McDonald, who pinch ran for Ricketts, made it to third base.

Then Vandever drove in McDonald and Wendy Trott added an RBI-double to make it a 6-0 lead.

“We never try to take off innings and we really try to score every inning,” Ricketts said. “I think we were really working to get the momentum back on our side after a couple of big defensive plays. We really wanted to keep momentum in our dugout, just go out and attack.”

Vandever finished 3-for-3 and Ricketts 1-for-3. Both drove in two runs.

OU managed 12 hits against Oregon with 10 coming off starter Alicia Cook, who shut the Sooners down in the Ducks’ 1-0 victory Feb. 23 at the Palm Springs (Calif.) Classic.

“They’ve got a nice mix of speed and power,” Oregon coach Kathy Arendsen said. “They had some timely hitting and they’re a very good team. We weren’t surprised by that. We knew coming in they were good, we’d seen them this year.”