Millas will undergo surgery Friday on his fractured left index finger, Spencer Nusbaum of The Athletic reports.
Millas had a procedure in July when he first suffered the injury, but he'll undergo another one Friday because the finger didn't heal as hoped. It will be the third surgery the catcher has had on the finger since last August. There's no word on a timeline for Millas' rehab, but he should be healed well before spring training.