Doug Fister. (AP Photo/Alex Brandon) Doug Fister. (AP Photo/Alex Brandon)

Back at Nationals Park after two extended spring training starts in Viera, Fla., Doug Fister threw a 40-pitch bullpen session on Thursday and “felt good,” Manager Matt Williams said. The next step is a four-inning/60-pitch minor league rehab start on Sunday, likely at Class A Potomac.

Fister, who is returning from a lat strain, wasn’t happy about some of his command, but Williams said that all concerned that him about the right-hander was how he felt physically.

“I know that the location will be there as he builds and he gets stronger and works into the fourth, fifth, sixth, seventh inning,” Williams said. “It’ll be there. I’m not concerned stuff-wise. I want to make sure he feels good about it.”

Pitching coach Steve McCatty also watched Fister throw and said he threw a good bullpen session.

“He feels fine,” McCatty said. “The velocity was better than last time. Pitching in Florida and all that, the velocity is normally a little bit down. Not a lot of adrenaline. Mechanically, he feels healthy and that’s the important thing. And he feels good. No problems.”

Fister is expected to throw five innings/75 pitches in his second rehab start, potentially his last one before rejoining the Nationals. If he needs only two rehab starts, he could slide into the rotation for his season debut around May 7.

>>> Gio Gonzalez left his Wednesday start after facing two batters in the sixth inning with minor left shoulder tightness in the chilly and windy conditions. The day after, Williams said, Gonzalez was dealing with normal soreness after a start. Gonzalez will receive treatment on Thursday, Williams said.

The most telling day will be when Gonzalez throws his bullpen session between starts. That is slated for Saturday.

“I’m not that concerned,” Williams said. “The fact that he could go out there and pitch and be fine. It wasn’t something where he went ‘ugh.’ It was just tightness. That happens to pitchers over the course of a season. I’m not concerned about it. I don’t think he is either really. We want to be careful, but we don’t think there’s any major concern there. ”

>>> Scott Hairston (oblique) is scheduled to take batting practice in the cages on Thursday, early batting practice Friday and then normal batting practice Saturday. He also will take part in outfield drills on Saturday, and then after that he likely will begin a minor league rehab assignment.

Williams said the backup outfielder reported no problems Thursday after taking his on-field batting practice the day before for the first time since the injury.