Byrnes injured his left hamstring in the second inning Monday attempting to steal third base.

Byrnes' hamstring is torn, and it is unknown when he will be back.

"It's going to be a while," manager Bob Melvin said.

Snyder was diagnosed with a testicular fracture after being struck by a foul ball two innings later and will require surgery.

"We're hopefully looking at the 15-day period where he's back after the All-Star break," Melvin said of Snyder.

Catcher Robby Hammock and right-hander Connor Robertson were called up from Class AAA Tucson in their places. Hammock didn't arrive to the ballpark until after the game started after getting late word.

Conor Jackson, the starting first baseman, will get the majority of time in left field, and Chad Tracy will play first base with Byrnes out. Miguel Montero will get the primary catching duties while Snyder is on the DL.

Robertson gave up one run in three innings of work in his debut for the Diamondbacks.

The injuries to Byrnes and Snyder have thinned an offense that is already struggling. There has been talk that the team will attempt to make a trade to bolster the offense.

BREWERS 8, DIAMONDBACKS 6: Milwaukee went ahead 7-1 early and held on to beat Arizona. J.J. Hardy hit two homers and knocked in three for the Brewers. Diamondbacks starter Randy Johnson gave up seven earned runs in 3 2/3 innings.