Zambrano was placed on the 15-day disabled list on Saturday, and will miss two starts, because of inflammation in his right shoulder. That means Zambrano will not pitch in the Interleague series between the Cubs and White Sox.
Guillen and Zambrano had dinner together at Zambrano's home, dining on Venezuelan dishes such as arepas, and the White Sox manager jokingly suggested the pitcher take the time off.
"I said, 'I may miss one start,'" Zambrano said. "He said, 'You better miss two.' I said, 'No, just one.' He said, 'Why don't you go on the DL and miss two starts?'"
Zambrano was scheduled to pitch next weekend when the intracity series shifts to U.S. Cellular Field.
He won't miss the verbal insults from White Sox fans either. Zambrano will just have to wait until next year to get a chance to pitch against the White Sox.
Told that Guillen wanted Zambrano on the sidelines, and not on the mound, Cubs manager Lou Piniella smiled.
"I don't blame him, actually," Piniella said.
The Cubs' rotation for the rematch next weekend at U.S. Cellular will be Ryan Dempster on Friday, Sean Gallagher on Saturday and Sean Marshall on Sunday. Marshall will be called up from Triple-A Iowa to take Zambrano's spot in the rotation on Tuesday in the Interleague series against the Baltimore Orioles.
On Saturday, Eric Patterson was called up from Iowa to take Zambrano's spot on the roster.
The Cubs were relieved that the injury was not serious.
"It's just a mild strain, and the doctors felt that by giving him a couple weeks, it'd be fine," Piniella said.
Zambrano had to come out of his last start Wednesday against Tampa Bay because of discomfort in his shoulder. An MR arthrogram on Friday confirmed there was no structural damage.
"There's nothing wrong," Zambrano said. "We just have to be careful and get some time and give it a rest and come back stronger and do my job."
He admitted he was a little upset at going on the DL.
"In this case, the most powerful word is the doctor and trainers," Zambrano said. "Obviously, they want the best for me -- [Cubs GM] Jim [Hendry] and everybody here -- and I appreciate that. Thank God, we've been playing good, and hopefully they can do a good job while I'm out."
The right-hander, who is 8-3 with a 3.13 ERA, was worried the injury was more serious.
"A little bit," Zambrano said. "This never happened to me, never happened to my arm. When it's the first time an injury happens to you, and you don't know what the injury is. You worry about it. As soon as you find out what's going on with your body, you can relax."
"We're obviously very relieved about yesterday's [MRA] announcement," Hendry said. "As you can expect, once he got the good news, Carlos felt like he could go, if not Tuesday, but the start after.
"It's our job to look at the calendar at the end of the year and work backwards," Hendry said. "I felt it was a good time to get it cleared up, get the inflammation out and have him fresh and ready to go for the next 18, 20 starts. It really wasn't a hard decision for us, knowing that the long haul is more important than the next 10 days."
The plan now is for Zambrano to rest, then throw on the side Monday, which is an off-day for the team.
What about his hitting? Zambrano, a switch-hitter, is batting .362 this season.
"If it affects my left-handed side, I'm a good hitter right-handed, too," Zambrano said.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.