KANSAS CITY -- Left-hander Danny Duffy was back in the Royals' clubhouse on Monday after a one-start rehab stint with Double-A Northwest Arkansas on Sunday.

Duffy, who is on the injured list because of a strained left hamstring, threw five innings and 72 pitches on Sunday, giving up one earned run.

“Everything went really well,” Duffy said. “The hamstring is fine. I just got done running three miles here. There should be no limitations.”

Manager Ned Yost said Duffy likely will be activated this weekend and probably start on Saturday.

“We’re probably going to go with a six-man rotation this week,” Yost said. “Give everyone an extra day’s rest. And that way, we can take another look at [Eric] Skoglund, too.”

Skoglund made his first Royals start this season on Sunday in Cleveland, going five innings and giving up just two hits and two runs. Yost said Skoglund likely will start on Friday.

If all falls into place, right-hander Brad Keller, who started Monday's series opener against the A's, will get an extra day of rest and pitch on Sunday.

But Yost said Keller will be on a pitch limit the rest of the way, capped at 100 pitches per outing. And it’s likely Keller will only get two more starts or so after Monday.

“We want to limit him to about 180 innings this year,” Yost said. “And then we can go up to 210 innings next year.”

Keller came into Monday’s start with 164 innings.

Mondesi getting closer

Yost also said shortstop Adalberto Mondesi, on the injured list because of a left shoulder subluxation, could be activated by Sunday, the first day of September callups.

Mondesi currently is rehabbing with Triple-A Omaha.

“There’s no reason to rush him and have to make a roster move before Sept. 1,” Yost said.

Yost reported that Mondesi has had no setbacks with his shoulder so far in his rehab assignment. But Mondesi is under orders not to make any more diving attempts in the field -- he sustained his injury diving head-first trying to catch a popup -- or on the bases the rest of the season.

“He can slide feet-first into bases,” Yost said. “Let’s just get through this season and let that thing totally heal in the offseason.”