Newcomb fought through it and played, though, delivering what proved to be the knockout blow in the Irish's 54-41 win over Tulsa East Central.
The title is McGuinness' ninth and first since 2008. It is also the Irish's first in Class 5A.
“We didn't get complacent,” Irish center Matt Christiansen said. “We worked out hardest, and now we've got what we were working for.”
Newcomb's lower lip was cut when he collided with another player in Friday's semifinal win over Carl Albert.
McGuinness trailed for much of the game before taking their first lead early in the third quarter.
East Central briefly regained the lead before Newcomb, left alone in the corner after two defenders collapsed on Christiansen, drilled a 3-pointer late in the third quarter that put the Irish ahead for good.
“He's a warrior,” McGuinness coach Tondrell Durham said of Newcomb.
Newcomb, still nursing the busted lip, couldn't speak after the game.
“It made me feel like I was a big part of the team,” he wrote in response to a question. “It made me feel great.”
Newcomb also played a big part in McGuinness' defensive plan — slowing down East Central's Kaleb Porter.
Porter had been dominant in the first two games of the tournament, scoring a combined 60 points in wins over Ardmore and Guthrie.
But the Irish locked Porter down from the outset, limiting him to just four first-half points, including his only first-half field goal in the final minute of the second quarter.
“The key to that was not letting him get any open windows whatsoever,” Christiansen said. “Mikey (Wilson) and Miles did an unbelievable job not giving him any space, not even letting him really see the ball.
“Granted, he's still an unbelievable player, he still had 15 points, but we held him back a little bit.”
Christiansen, who nearly had a triple-double in the semifinals, was just as dominant in the title game.
The San Francisco signee, had 12 points, 19 rebounds and 6 blocks in shutting down the inside yet again.
“Offensively, if we can get 8-10 points out of Matt, that's great,” Joe Edmonds said. “But when he gets (19) rebounds and (6) blocks, no one can beat us.”
Matthew Ross had 15 and Edmonds added 13 points for the Irish.
“There's so many teams whenever you start, and you all have one goal. To be that team at the end that makes it, it's the best team in the world,” Ross said.