As the biggest game of his basketball career unfolded Thursday night, Gonzaga’s Sam Miller sat stewing on the bench, watching as his teammates traded blows with DeMatha in a thrilling marathon of a Washington Catholic Athletic Conference boys’ basketball championship.

The Eagles senior had determined that a nagging ankle injury wouldn’t hold him back in the all-or-nothing contest, but when foul trouble sent him to the bench during a critical portion of the second half, Miller was left to ponder just how he could impact what had turned into a contest of wills.

“I knew I would get back in the game eventually. When I did, my coaches told me I had to step up,” Miller said. “Once I got there, I was just in the moment.”

Each time the moment called for a big shot, Miller delivered. The Dayton recruit scored 15 of his 19 points in the fourth quarter and two overtime periods to lift No. 7 Gonzaga to the WCAC crown, 77-68, over No. 2 DeMatha before a packed house at Bender Arena.

After scoring the game’s first bucket, Miller faded to the background of a first half defined by its frenetic pace and runs. After Gonzaga (21-10) opened the second quarter with a 7-0 spurt that helped the Eagles build a 31-29 halftime lead, DeMatha (27-4) emerged from the locker room and stole back the momentum with an 8-0 run of its own behind the play of D.J. Harvey.

The Eagles were able to out duel the Stags in a double overtime thriller, while the Lady Panthers clawed their way to an undefeated conference season. (Video by Julian Toliver for Synthesis/Koubaroulis LLC./The Washington Post)

The Stags’ lead grew to 13 following a Nate Darling three-pointer to start the fourth quarter.

But two of the Eagles’ youngest weapons in freshman Prentiss Hubb and sophomore Chris Lykes shook off their nerves to propel their team. After Hubb scored nine straight points, Lykes knocked down consecutive buckets, including a long three-pointer that tied the score at 51 with just under four minutes to play.

“I was very nervous, but I tried my best not to show it,” said Lykes, who finished with 20 points. “I guess I did a decent job of it and I just wanted to give my all so that in the end, no matter the outcome, I would be satisfied with the effort I gave.”

That outcome would remain in limbo for two extra sessions. A Miller bucket was followed up by two Markelle Fultz free throws to force the first overtime. Bolstered by the second wind from his time on the bench, Miller went on to score all seven of Gonzaga’s points in the initial extra session, including a three-pointer that tied the game at 60.

“I had to hit those shots if we wanted to win, so that’s what I told myself,” Miller said. “And thankfully I made them.”

Lykes and Bryant Crawford added two more threes to start the second overtime and put the Eagles ahead by six, a lead that proved too much for a Stags team fighting fatigue and struggling through a 13-for-21 performance at the foul line.

Meanwhile, as Gonzaga iced the championship with steady free throw shooting, its fans crowded along the baseline, ready to burst in jubilation over their first conference title since 2008.

“This is just amazing,” Miller said. “We fought, we scrapped and we came up with big shots to get the job done.”