CHICAGO -- The Cubs will activate pitcher Matt Garza off the disabled list on Tuesday to start that night against the Pittsburgh Pirates, manager Dale Sveum said before Saturday's game.

"I'm excited and happy I don't have to rehab again," Garza said. "This actually means something, so I can't wait. It's been 10 months in the making, I'm excited to get back out there."

An elbow injury sidelined Garza last July, and while rehabbing this spring, he suffered a lat strain and has been on the disabled list since the start of the season. Tuesday will mark his first start since July 21, 2012.

Garza tossed 75 pitches in six shutout innings at Triple-A Iowa on Thursday night, which he believed was the outing he needed to convince the Cubs he was ready to compete at the big-league level.

Garza hoped that there would be no limitations put on him, but Sveum said Garza would likely be held to around 85 to 90 pitches in his first start.

Garza said he felt no trepidation about returning to the rotation.

"The only time I was actually nervous was my first start in Tennessee," Garza said. "The first couple pitches I was kind of nervous and feeling around. But since then there's no doubt in my mind that this is what I'm supposed to do."

To make room for Garza in the rotation, Carlos Villanueva will be moved to the bullpen.

"He was very professional about it, he understood," Sveum said when asked how Villanueva took the news. "He's always been in this type of role, the swing man, so to speak. So he understands it and he accepts it. Very professional about the whole thing."

Villanueva has a 3.76 career ERA as a reliever in 342 1/3 innings. He had compiled a 3.93 ERA in 52 2/3 innings this season with the Cubs, all as a starter. However, his ERA had jumped in each of his previous four starts, culminating in a five inning, 12-hit, seven run performance against the Colorado Rockies on Tuesday night.

No corresponding move has been announced to make room for Garza on the 25-man roster.

Garza said this was the longest he's been away from pitching as a professional and that he leaned on his family to get through the difficult period.

"It was tough, but I had my family, my wife and kids there to help me through it," Garza said. "It was a grind mentally. Physically I can do anything, but the mental part was the tough part. It was one setback after another. I was like, 'Man, just keep going, keep going, there's a prize at the end of it.' I'm just happy I'm here at the end of it and can't wait until Tuesday."

In two seasons with the Cubs, Garza has made 49 starts, tossing 301 2/3 innings, striking out 293, while walking 95 with a 3.52 ERA.