Diaz, who missed two months with a fractured left foot earlier this season, struggled to field a soft grounder in the top of the first inning Monday and struck out in the bottom of the frame.
"Sore, but I think he's OK," Rays manager Kevin Cash said in assessing Diaz. "The play in the first inning that [Yordan] Alvarez hit, that was our concern going in and playing him, whether it's first or third base, just that quick agility movement. When you're running, when you hit a ball, you kind of have the thought process to go run.
"Well, when a ball kind of comes off a bat, you're not sure which way it's going to go, I think that really grabbed his foot. But we went and had the doctor look at it. He seems to be fine."
When Diaz's spot in the batting order came back up in the second inning, the Rays replaced him with Matt Duffy.
Diaz suffered the initial injury to his left foot on July 22 and was sidelined until Sept. 29, when he was activated for the last game of the regular season.
He played first base last week in the wild-card game against Oakland and has started as the DH and third baseman, respectively, in the first two games of this series against Houston.