"These kids have earned it," Tower Hill coach Billy Cannon said. "They've worked their butts off all year long."
The Hillers (20-1) won their first 19 games this season before losing the regular-season finale to Tatnall last Friday.
"I think that loss was probably a blessing in disguise," Cannon said. "It gave us the sense of a pressure situation, and the kids responded."
Tower Hill senior ace Will Stratton (9-0) didn't give up a hit until the fifth inning. He had eight strikeouts, and twice ended an inning with a strikeout when the Riders had the bases loaded, including the game's final out.
The Hillers were ahead 6-1 when the Riders batted around in the fifth to make it 6-4. Stratton ran a 3-0 count before notching a strikeout to end that rally.
In the bottom of the sixth, Tower Hill manufactured what proved to be the winning run. James Mraz doubled, Beau Reese sacrificed him to third and Mraz scored on Garrett Lyons' fly for a 7-4 lead.
Caesar Rodney rallied to score twice with two outs in the seventh. Will Ross singled home Greg McKee to make it 7-6, and Stephen Sherlock's walk loaded the bases.
Stratton struck out the next batter, pushing No. 7 seed Tower Hill into Thursday's quarterfinals, where the Hillers will face No. 2 seed and defending champion Caravel (19-2) at a site and time to be determined.
"With the bases loaded and giving up a couple hits," Stratton said, "you just stay with your game plan, stay focused and challenge them with my best pitch."
As for the last pitch to the last batter, Stratton really had only one choice.
"Fastball," he said. "I just went back to the fastball. If I'm going to lose, it's going to be on my No. 1 pitch."
Tower Hill's Brett Smith was 3-for-3 with a single, double and home run.
For No. 10 Caesar Rodney (14-7), McKee was 2-for-3 with a walk.
"Down 6-1 to a pitcher of that ability," CR coach John Newman said, "is a tough road, and I'm proud of the kids."
Tower Hill 7, Caesar Rodney 6
Caesar Rodney (14-7) 010 030 2-6 8 0
Tower Hill (20-1) 402 001 x-7 13 2
CR: Lust, Brosius (4) and Babuca. TH: Stratton and Anderson. W-Stratton (9-0). L-Lust (7-2).
2B-CR: Brittingham; TH: Smith, Mraz. 3B-TH: Boselli, Harper. HR-TH: Smith.