Rays manager Joe Maddon said Guyer staying in the game ended up being key to the win.
"The part about that that's gotten lost is the fact that by him continuing to play, it permitted us to keep Desmond [Jennings] on the bench later in the game. We eventually pinch hit him for [David] DeJesus, which eventually led to that winning rally."
The timing of the injury is especially unfortunate for the 28-year-old, who appeared to have found his swing of late. Guyer hit .370 (10-for-27) with a home run and four RBIs in his past 10 games.
Maddon said the outfielder was discouraged to learn that his thumb was fractured following tests performed postgame Sunday, but the injury won't likely lead to an extended stay on the DL.
"He's really becoming a big league player right now," said Maddon. "This guy has faced a lot of adversity over the past couple of years, so it's not easy for him to accept this right now. He was pretty distraught after the game, and I don't blame him. But we're trying to encourage him and have him understand that he's really turning the corner."