BIDDEFORD — Nate McKeown discovered his offensive groove at just the right time.

The Biddeford senior had two hits, including a double that drove in a pair, to lead the Tigers to a 9-2 win over South Portland in a Western Maine Class A preliminary round high school baseball game, played at St. Louis Field Tuesday.

“I saw the ball well today, a lot better than usual,” said McKeown, who hit .209 in 14 games during the regular season. “I’m not sure why, but it started working today.

“It felt good to do what I was trying to do all year.”

McKeown’s double in the fifth served to blow a close game wide open. Biddeford owned a 3-1 advantage heading into the inning. McKeown’s extra-base hit punctuated a nine-pitch at-bat and upped the count to 5-1.

“I felt like throughout the year (McKeown) had some good swings,” said Biddeford coach Keith Leblanc. “He has a tendency to look at a lot of pitches going by, and today, I felt like he was seeing the ball well and right on those pitches. Even the pitches he was fouling off (prior to doubling), the swing looked good and he was ready to have a good at-bat.”

Zach Jacques supplied a sacrifice fly to complete the three-run fifth inning and give the Tigers a 6-1 lead.

The sixth-seeded Tigers (9-8) advance to face No. 3 Windham (12-4) in the Western Maine Class A quarterfinals on Thursday. South Portland, the 11th seed, completed its season 6-11.

Biddeford took control of a 1-1 game in the fourth inning.

South Portland threatened to go ahead in the top half of the inning but a good defensive play by the Tigers closed out the frame. The Red Riots had runners at first and second with two outs when Shawn Shannon singled to left. Nick Leblond fielded the ball cleanly and threw a strike into the infield that caught John Vickers on a wide turn rounding third. Vickers was tagged out after a quick rundown and Biddeford escaped unscathed.

“We teach to try and throw right through the cutoff man’s head and (Leblond) threw a strike,” said Leblanc. “(Vickers) was pretty aggressive taking that turn and (shortstop) Patrick Wilson was head’s up in covering third. It was just a team play that we practice and it went to perfection.”

The Tigers scored twice in the bottom half of the inning to assume control of the game. McKeown led off the inning with a walk and moved to second when South Portland first baseman Jordan Muller caught an infield fly and then stepped into an area on the secondary field deemed out of play. Jacques then reached on an error to move McKeown to third. A sacrifice fly by Corey Brown, followed by a single by Matt McGuirk, pushed home both runners and gave Biddeford a 3-1 lead.

“Those were the type of plays they made today, and we didn’t,” said South Portland coach Mike Owens.

“They put us in those situations, and they forced those mistakes to hurt. We had some bad breaks but we caused a lot of them.”

The Tigers added three runs in each of the fifth and sixth innings to make it 9-1 before South Portland scored in the seventh to complete the scoring.

Bobby Cote started and posted the win for the Tigers, allowing one run on three hits in six innings.

South Portland starter Matt DiBiase took the loss after giving up six runs on eight hits in four-plus innings.