Gallen (thumb) is expected to start Saturday against the Mets, Nick Piecoro of the Arizona Republic reports.
The 26-year-old was scheduled to start Tuesday against the Astros and had the outing pushed back due to a laceration on his right thumb, but he's set to make his season debut just a few days later. Gallen indicated he still could have pitched Tuesday, but the Diamondbacks opted to play it safe and delay his first start of 2022.