Giants purchased the contract of C Tony Sanchez from Triple-A Sacramento.
Sanchez will serve as emergency depth at catcher for the Giants over their final six regular-season games. The former Pirates prospect hit .200/.317/.340 in 60 plate appearances with Sacramento.
Giants designated RHP Matt Reynolds for assignment.
The move clears a 40-man roster spot for Tony Sanchez, who joined the Giants as an emergency backup catcher on Tuesday. Reynolds allowed five earned runs on seven hits and five walks in six innings this season out of the San Francisco bullpen.
Giants placed OF Mac Williamson on the 60-day disabled list with a strained quad.
Williamson suffered the injury Sunday in San Diego and is officially done for the season. He finishes the 2016 campaign with a .223/.315/.411 batting line in 54 major league games.
Eduardo Nunez (hamstring) is only expected to miss 2-3 days.
Nunez was sent for an MRI on Monday after injuring his right hamstring on a slide in Sunday's series finale against the Padres. The exam apparently showed nothing serious. Conor Gillaspie is starting at third base for the Giants on Tuesday night against Colorado.
Johnny Cueto (groin) has been cleared to start Thursday at home against the Rockies.
Cueto suffered a mild groin strain in his September 20 start at Dodger Stadium, but he made it through a bullpen session Tuesday without issue and was given the go-ahead to pitch Thursday by San Francisco manager Bruce Bochy. It could be a very important game for the Wild Card-hunting Giants.