CHICAGO -- The Cubs added reinforcements to the bullpen on Tuesday, recalling relievers James Russell and Jeff Stevens from Triple-A Iowa to replace lefty John Grabow and Carlos Zambrano on the 25-man roster.

Grabow was placed on the 15-day disabled list with a moderate sprain of his left knee, which he suffered Monday. Grabow had just come off the disabled list June 16 because of the knee, but aggravated it on a pitch Monday. He will be sidelined a minimum of three weeks.

Zambrano was placed on the restricted list to get treatment for anger issues, something coordinated by the Cubs, Major League Baseball, the Players Association and the pitcher's agent following his dugout tirade on Friday.

Zambrano was suspended without pay after the tantrum, and by switching to the restricted list, the Cubs can add a pitcher to the roster. Zambrano will be evaluated by doctors and given a program to follow. If all goes well, he would rejoin the Cubs after the All-Star break.

Chicago now has four rookies in the bullpen in Russell, Stevens, Andrew Cashner and Brian Schlitter.

"As an organization, I think we're a little further along with the arms we have," Cubs manager Lou Piniella said. "We bring them up and they compete and do a nice job. Actually, my young players are doing well also. Our young players aren't the reason we're not winning ballgames."

Russell began the season with the big league team and posted a 2.33 ERA in his first 17 outings with the Cubs.

"Back to work," Russell said.

The lefty, who was optioned to the Minor League team on June 12, had a 5.73 ERA in five relief outings at Iowa.

"It's a tough deal with Grabow going down -- you don't want to see that," Russell said.

At Iowa, Russell fine-tuned his pitches.

"I just worked on locating my fastball better, and I had to figure out my changeup, because it kind of left me for a while," Russell said. "Overall, I built off what I did up here."

Stevens had been sent down to Iowa on Saturday because the Cubs needed a fresh arm following Friday's game. Zambrano lasted one inning and was then sent home because of his outburst.

"I understood the move and wasn't too upset," Stevens said.

Stevens never got into a game with the Iowa Cubs this time because he spent Sunday traveling from Chicago to New Orleans, but never made it and spent that night in Miami. On Monday, he joined the Iowa Cubs in New Orleans, but that game was postponed because of rain.

"I played catch," Stevens said. "I did rack up some frequent flyer miles."

He had no record and a 2.81 ERA in 14 Major League relief appearances this season, holding batters to a .230 average.

"They said, 'Go down, and we'll get you back here as soon as we can,'" Stevens said of the message he got Saturday. "I didn't know if it would be two days, two weeks, two months."

Soriano reaches out to Zambrano

CHICAGO -- Alfonso Soriano has tried three times to reach teammate Carlos Zambrano and had no luck, but he plans to try again Friday.

"Just in case he answers," Soriano said.

Zambrano was placed on the restricted list Tuesday. He was scheduled to meet Wednesday in New York with doctors selected by Major League Baseball and the Players Association to help him deal with anger issues. What type of counseling he will receive or program he'll be placed on will then be determined. He will not rejoin the Cubs until after the All-Star break.

"I'm very happy that he has somebody to help him," Soriano said, "and I hope when he comes back, he can be 100 percent and help the team win."

Soriano tried to call Zambrano after the tantrum happened on Friday at U.S. Cellular Field, but had the wrong number. He tried again Sunday, but Zambrano didn't answer.

"Sometimes he can't control his emotions," Soriano said. "That's his problem, but other than that, he's a great guy. I hope everybody gives him support, because he's part of the team."

The Cubs now need to focus on the National League Central. They entered play Tuesday 9 1/2 games back.

"We have a lot of things to do," Soriano said. "We're not playing good right now and we have to find a way to play better."

Piniella to ride hot hand at leadoff spot

CHICAGO -- The Cubs have tried four different players in the leadoff spot this season, but don't have one guy to turn to.

"In a true sense, [do we have] somebody who's going to steal 40 bases? No," Cubs manager Lou Piniella said. "Somebody who should be able to swing the bat with consistency and have a decent on-base percentage -- we should have that, yes."

So far, Ryan Theriot has led off the most, doing so in 48 games. Kosuke Fukudome was at the top of the order Tuesday for the 22nd time this season, while Marlon Byrd has led off five times and Tyler Colvin twice.

"Whoever's hot, whatever the matchups look like," Piniella said about how he picks the leadoff man.

And if he can't make up his mind?

"If I'm undecided, I'll ask [bench coach Alan Trammell] what he thinks," Piniella said.

Colvin offers Cubs some options

CHICAGO -- Cubs rookie Tyler Colvin played first base in high school and some in college, but now he is an outfielder. Could he take over at first?

"Basically, when you look at Colvin, a left-hand thrower, he would fit nicely in left field," Cubs manager Lou Piniella said. "He's an athletic kid. Put it this way, he has some athleticism, no question."

The Cubs will be looking for a first baseman in 2011 unless they re-sign Derrek Lee, who will be a free agent after this season. For now, they'll leave Colvin in the outfield. But where does he fit in the lineup? So far, the rookie has batted first, second, fourth, fifth, sixth, seventh and eighth.

"He's leading the team in home runs per at-bats," Piniella said of Colvin, who has one homer per 13.90 at-bats, tops among rookies with at least 100 at-bats this year.

"In this lineup, he can hit just about anywhere," Piniella said. "He can hit second. He probably runs as well as anybody we have. He can hit in the middle of the lineup because he hits some home runs.

"Long term, there's no reason Colvin can't be a fifth or sixth hitter, maybe a two or three hitter if his on-base percentages are good and he keeps improving," Piniella said.