Mazzaro threw 1.1 innings Thursday, striking out one and allowing no runs in Triple-A Sacramento's game against Salt Lake.
Mazzaro had a rocky spring training, allowing four earned runs and 11 hits in 5.0 innings of work. He isn't currently on the Giants' 40-man roster, but has bounced between the minors and majors for the last few years with moderate success, so it wouldn't be a surprise if he found his way there again this season.