Happ (hamstring) is starting in left field and batting second Tuesday against the Astros, Matt Kawahara of the Houston Chronicle reports.
The 29-year-old sat out Saturday and Sunday with hamstring soreness after exiting Friday's contest, but he's ready to retake the field following Monday's team off day. Happ has been in a slump over his past nine games, going 4-for-35 after he posted a .933 OPS in his first 40 at-bats of the campaign.