Charlie Morton allowed four runs on nine hits over five innings in Wednesday's no-decision against the Giants.
Pedro Alvarez is not in the Pirates' lineup Wednesday for the second straight game.
Josh Harrison homered in his third consecutive game, helping the Pirates to a 3-1 win over the Giants on Tuesday.
Francisco Liriano struck out 11 Giants, yielding one run over seven innings to earn his third victory on Tuesday.
Pirates manager Clint Hurdle said Tuesday that he's "not optimistic" Starling Marte (concussion) will be activated from the disabled list when first eligible on Wednesday.
Gerrit Cole (lat) tossed five scoreless innings Monday in his first minor league rehab start with Triple-A Indianapolis.
Josh Harrison finished 2-for-3 with a walk, solo homer and two runs scored in Monday's win against the Giants.
Vance Worley tossed his first career shutout, allowing only four hits, in a 5-0 victory against the Giants on Monday.
Josh Harrison had a monster day on Sunday, going 4-for-6 with a home run, two RBI, two runs scored and two stolen bases in the Pirates' 7-5 victory over the Rockies.
Mark Melancon struck out two in a scoreless ninth inning to pick up the save against the Rockies on Sunday.
Edinson Volquez lasted just 4 1/3 innings in a no-decision against the Rockies on Sunday, allowing four runs -- two earned -- on six hits.
Pedro Alvarez is back in the Pirates' lineup Sunday.
Gregory Polanco was moved down to the No. 7 spot in the batting order during Saturday's loss to the Rockies.
Jeff Locke was lit up for six earned runs in 6 2/3 innings Saturday in a loss to the Rockies.
Gerrit Cole (lat) will need a second minor league rehab start after his first one on Monday.