Mathias (shoulder) will start at third base and bat sixth in Monday's split-squad Cactus League game against the Brewers.
The non-roster invitee will be making his second start in as many days after he went 0-for-3 while manning the keystone for five innings in Sunday's 9-4 win over the Angels. Mathias finished the 2023 campaign on the Giants' 60-day injured list due to a right shoulder strain, but he looks to be back to full health as the start of the 2024 season nears.