To make room for Wood on the roster, the club designated pitcher Scott Eyre for assignment.
Wood pitched the eighth inning of the Cubs' 11-7 win against Houston, giving up one hit and no runs. Wood did not discuss his outing, only saying, "It's great to be back," after the game. Piniella said Wood felt fine after the seven-pitch setup appearance.
"We'll give him one more game in that type of role and he'll be able to get back to the closer's role," Piniella said.
Wood, who had not pitched since July 11 because of a blister on his right index finger, met with Piniella and pitching coach Larry Rothschild on Monday. Wood had thrown a simulated game Sunday at Wrigley Field, and the three discussed the next step.
Wood lobbied to be reinstated Monday night for the first of three games against the Houston Astros.
"I tried, and it didn't work too well," Wood said.
Carlos Marmol, Bob Howry or rookie Jeff Samardzija will hold down the closer duties until Wood throws in one more tuneup game. Marmol pitched the ninth with a four-run lead on Tuesday.
"He's the manager," Wood said. "I'm going to do what he says. I just want to get back out there and pitch."
Wood and the Cubs' medical staff tried every salve and remedy possible, some conventional and some not, to heal the blister. Anyone who doubts something so small could sideline him for so long has never been a pitcher.
"The chances are the people who are saying that have never picked up a baseball or thrown one," Wood said. "I can't worry about what people say. People in the game who have had it before know what I'm doing. That's all that matters to me. I'm looking forward to getting back out there."
The time off should benefit Wood, who has 24 saves in 29 opportunities. He originally thought he'd be back immediately after the All-Star break.
"I got a little longer break -- I didn't want one, but I did get one," Wood said. "I should be strong for the stretch.
"It's frustrating when it's something as small as this. Any time you miss games and you're not part of the action and you're in a pennant race, it's no fun to sit and watch. I guess it made it a little easier, because of the way we were playing."
What actually healed the blister?
"I can't tell you," Wood said with a smile.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.