Ohlendorf, who is on the 15-day disabled list with back spasms, threw fastballs and changeups on Saturday.
"It went well," said Ohlendorf, who said he felt no pain or soreness.
On Sunday, Ohlendorf will throw between 30-40 pitches on a full mound.
Ohlendorf (0-3, 3.60 ERA in one start) is eligible to come off the DL on Tuesday but will not be activated on that date. If everything goes well on Sunday, Ohlendorf, who went 11-10 with a 3.92 ERA last season in his first full season with Pittsburgh, will throw another side session in Milwaukee on Tuesday. That will consist of three sets of 15 pitches, separated by five-minute breaks.
"We'll see how his back reacts to the up and down, on and off," said Pirates pitching coach Joe Kerrigan. "[We need to] get him used to that before he goes out."
Before pitching for the Pirates, Ohlendorf will make a rehab start in the Minors.
"I would think it would be coming up quickly," said Ohlendorf.