No one would have expected less from bitter Ches-Mont League National Division rivals.

West Chester Henderson and Downingtown East, squaring off in a PIAA Class AAAA baseball quarterfinal Thursday, battled for nine innings and more than three hours.

In the end, Scott Fenton's three-run homer to left field, traveling about 360 feet, in the top of the ninth gave the Warriors a thrilling 9-7 victory over the Cougars in 3 hours, 4 minutes at Everett Swanson Field on the Glen Mills campus.

"It was a fastball right down the pipe," Fenton said of reliever Chris Ward's 0-1 pitch. "I got a good piece of the ball. I was seeing it well today."

For Fenton, a 6-foot-3, 175-pound senior rightfielder and catcher, it was just the second home run of the season.

"Every once in a while, he'll come up with that big hit," teammate Sean McCormick said.

Advancing to the state Final Four, Henderson, 24-3 and ranked No. 2 in Southeastern Pennsylvania by The Inquirer, will play Pine Richland in a semifinal Monday at a neutral site and time to be determined.

"It's been an absolute dream," Warriors coach Luke McNichol said of his team's drive to the state semis. "And I just don't want to wake up. This game was like Frazier and Ali slugging it out."

No. 9 East, which closed with an 18-7 record, rallied in the bottom of the seventh from a 6-4 deficit. The equalizer was Luke Alba's two-run homer to center field. The ball sailed about 385 feet.

Henderson and East split during the regular season, with the Cougars winning by 6-4 on April 9 and the Warriors recording a 6-5 victory on May 5.

"This was the game to see who was better," said McCormick, who was at shortstop and pitcher and in left field in the latest clash.

McCormick, a senior leadoff man bound for Kutztown, went 2 for 5 with a run scored. His single in the fifth scored Fenton. He pitched 11/3 innings of relief, surrendering Alba's two-run shot.

Henderson, runner-up to Council Rock North in the District 1 tournament, went ahead, 5-2, in the sixth. Chas McCormick, a freshman centerfielder and Sean's brother, produced a two-run double to right.

"He's doing great this year," Sean McCormick said. "I'd say he's one of the best hitters in our league. His composure for a freshman is incredible."

In the ninth, John Iezzi, a senior lefthander who earned the win in relief, drew a one-out walk. After a strikeout, Chas McCormick kept things alive with a single to right-center. Fenton then provided the blast that made it 9-6.

The Cougars scratched out a run in their last at-bat. Then, with two outs and the bases loaded, Iezzi got Nick Salvano, who had slammed a two-run homer to left in the fifth off lefthanded starter Kyle Hooven, to pop up to second baseman Ryan O'Connell.

W.C. Henderson 200 012 103 - 9 17 2

Downingtown East 000 022 201 - 7 11 1

WP: John Iezzi. LP: Chris Ward. 2B: DE-Tory Sarpen; WCH-Chas McCormick. HR: DE-Nick Salvano, Luke Alba; WCH-Scott Fenton.

Contact staff writer Rick O'Brien at 610-313-8019 or robrien@phillynews.com.