Manager Mike Shildt told reporters Sunday that Matsui is dealing with back spasms and will not pitch against the Cubs, Dennis Lin of The Athletic reports.
Matsui felt his back tighten up Saturday and is considered day-to-day. He joined the Padres in December on a five-year, $28 million contract after spending the last several years in the Nippon Professional Baseball league with the Rakuten Eagles. In 2023, Matsui posted 39 saves and a 2-3 record over 59 appearances while registering a 1.57 ERA, 0.89 WHIP and 72 strikeouts over 57.1 innings.