CHICAGO -- Cubs pitcher Mark Prior got the go-ahead to play catch, and he did so on Friday at Wrigley Field, ending the first week of his throwing program.

Prior, who underwent arthroscopic surgery on his right shoulder on April 24, had flown to Birmingham, Ala., to be re-examined by Dr. James Andrews, who performed the procedure.

"The doctor gave me good news and cleared me to start doing my throwing program," Prior said Friday. "I started doing my tossing on Monday. It's three days a week, and today was the third day, and so far, so good."

During the arthroscopy in April, Andrews did a debridement of Prior's right rotator cuff and repaired the labral and capsular injuries in his right shoulder. Prior is a little ahead of schedule in his rehab, which has not included any throwing until this week.

"They originally said six months, but my goal was around five, if everything went well," Prior said. "[Andrews] saw me Sunday, Monday morning, and said it looked great and just to get going. We'll just take the long, slow throwing program and get going."

Prior fully expects to return.

"The goal is, obviously, to come back," said Prior, who was 18-6 with a 2.43 ERA in 2003, the last time the Cubs won the division. "I expect to come back. This day and age playing, we're fortunate to have medicine and technology that gives us a second chance."

Limited to nine starts last season because of his troublesome shoulder, Prior was headed back to San Diego on Saturday to resume his throwing program and get "back to work."

Cub fans who watch games on TV will be happy to know he understands their anxiety. It's been difficult for him to follow the team's race for the postseason from far away.

"I've been watching the guys all year, and it's tough being away and watching it," Prior said. "It's like getting an ulcer -- some of these games are interesting. The guys are playing good and are in a very good position. The next nine, eight days will be fun to watch. They're playing well, so it should be good."

The Cubs beat the Pittsburgh Pirates, 13-8, on Friday in a wild and crazy game, but they've had 31 one-run games since May 28, and are 21-10 in that stretch. That can be nerve-wracking.

"It's easier to be in the clubhouse watching than watching on TV," Prior said. "You don't get that same feel for the game as you would being here. Today was an interesting game, but it's like no big deal when you're here. On TV, it's a different ballgame."

Ulcers? Prior just turned 27. Cubs manager Lou Piniella said he's tempted to drink Maalox.

"I'm too young for Maalox," Prior said.