CHICAGO -- Cubs ace Carlos Zambrano has right rotator cuff tendinitis and inflammation, an MRI confirmed Thursday, a potential obstacle to Chicago's chances of winning the World Series for the first time in a century.
Zambrano received a shot of anti-inflammatory medication and hopes to return to the rotation next week.
General manager Jim Hendry said Zambrano hopes to start throwing again when the team begins a series in St. Louis on Sept. 10. If all goes well, Zambrano would start at Houston in the following series.
Zambrano, 13-5 this year, left his start Tuesday night against the Astros after five innings, saying he did not feel well. He was examined Wednesday by team orthopedist Dr. Stephen Gryzlo.
Zambrano is 1-1 over his last six starts and has made it past the fifth inning only twice.
Sean Marshall will start in Zambrano's place this Sunday at Cincinnati. The Cubs began the day with a 4½-game lead in the NL Central and have 22 games remaining, including 16 on the road.
"Hopefully he will be just missing this one start," Hendry said. "I think it's a relief that Z doesn't have anything more significant than what we thought."
Zambrano was on the disabled list in June with a sore shoulder.
"Obviously Dr. Gryzlo has been right on with all his evaluations," Hendry said. "He felt this was not going to be a significant problem, not a situation where he had to put on the DL."