Mostert (knee) didn't participate in Thursday's practice, Jennifer Lee Chan of NBC Sports Bay Area reports.
Mostert wasn't in attendance for the 49ers' second practice in a row, with Matt Barrows of The Athletic relaying that the running back left the team and headed to Cleveland to witness the birth of his second child. The 49ers may not even ask Mostert to return to the East Coast before Sunday's game against the Giants, as the running back wasn't expected to be available for the contest anyway after suffering a sprained MCL during the Week 2 win over the Jets. The injury isn't believed to be a major concern, as Mostert could be a candidate to play Week 4 against Philadelphia if he's able to get back on the practice field in some capacity. At least for the Week 3 matchup, however, the 49ers will likely lean on Jerick McKinnon and Jeff Wilson to handle most of the reps out of the backfield.