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.