The next morning in Defense Against the Dark Arts, while copying down different ways of treating werewolf bites, Harry and Ron were still discussing what they'd do with a Sorcerer's Stone if they had one. It wasn't until Ron said he'd buy his own Quidditch team that Harry remembered about Snape and the coming match.

“I'm going to play,” he told Ron and Hermione. “If I don't, all the Slytherins will think I'm just too scared to face Snape. I'll show them… it'll really wipe the smiles off their faces if we win.”

“Just as long as we're not wiping you off the field,” said Hermione.