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8/29/2014 8:30 P.M. ET

Rizzo sits for third straight game with tight back

ST. LOUIS -- Cubs first baseman Anthony Rizzo, who had hoped to return for the start of the Cardinals series on Friday night, did not start for a third straight game because of tightness in his lower back.

Cubs manager Rick Renteria said Rizzo was better than he was on Thursday. Whether he'll be able to play in one of the Cubs' doubleheader games on Saturday is to be determined.

Rizzo's back became an issue on Tuesday when he couldn't get loose after a 50-minute rain delay in Cincinnati. He came out of that game as a precaution.

Rizzo has yet to be in the lineup since top prospect Jorge Soler was promoted from Triple-A Iowa.

"We all want to see [Rizzo] in that lineup," Cubs general manager Jed Hoyer said. "It'll be fun to see that lineup card. I don't have a prognosis [on Rizzo's status], just that he's day to day in the true sense of the word."

On Thursday, Rizzo said there wasn't one thing that aggravated his back, and called the problem "frustrating."

Bryant will not join Cubs when rosters expand

ST. LOUIS -- Cubs fans eager to see Kris Bryant in the same lineup as Javier Baez, Jorge Soler, Anthony Rizzo and Starlin Castro will have to wait.

General manager Jed Hoyer repeated Friday that Bryant, No. 1 on MLB.com's Top 20 Cubs prospects list, will finish his season at Triple-A Iowa and not be one of the players added when big league rosters expand on Monday.

Hoyer would not say which players will be added. Iowa has four regular-season games remaining and has a chance to make the playoffs.

Bryant, 22, batted .355 with 22 home runs and 20 doubles at Double-A Tennessee, and was batting .300 with 21 homers and 14 doubles in 66 games at Iowa entering Friday. The second player taken overall in the 2013 First-Year Player Draft, Bryant is not on the Cubs' 40-man roster.

"He's not on the roster, so right away [if he was called up] that would knock off another player off the roster," Hoyer said Friday. "We're going to be really tight with the roster, and we know that. We feel in his first full season, he's going to get 140 plus games, he's played exceptionally well -- nothing has changed on that front [as far as calling him up]."

The fact that Bryant has done so well in his first year of professional baseball has made Cubs fans giddy about the prospect of seeing the third baseman at Wrigley Field.

"The most impressive thing about his season has been the consistency," Hoyer said. "The slumps have been really quick. He deserves a lot of credit for being able to make adjustments quickly. I think he's very level-headed as a person. He doesn't get too down.

"We've never wavered on [the decision to leave him in the Minors]. We feel it's the right thing for him -- first full season, not on the roster -- and we'll enjoy the guys we have up here now."

Are the Cubs hesitating to avoid starting the clock on Bryant's service time? Hoyer said that wasn't a factor.

"That's not the reason or a concern," he said.

Cubs to begin homestand with JRW celebration

ST. LOUIS -- The Cubs will salute the Jackie Robinson West Little League team on Monday at Wrigley Field.

The Chicago team, which won the U.S. Little League championship and finished second in the World Series to Seoul, South Korea, will meet some of the Cubs players during batting practice before their game against the Brewers.

The Little League team will be honored pregame, throw ceremonial first pitches, then sing during the seventh-inning stretch from the field.

Cubs pitchers Wesley Wright and Edwin Jackson were among the Major League players who donated money to help the families of the Little Leaguers attend the tournament in Williamsport, Pa.

Monday's contest opens a six-game homestand for the Cubs, who will honor the 2000s with decade-themed promotional giveaways, specialty food and beverage offerings and entertainment. It's all part of the season-long celebration of Wrigley Field's 100th anniversary. On Sept. 5, Hall of Famer Greg Maddux will be recognized with a 3,000th strikeout bobblehead for the first 10,000 fans.

Fans coming to Wrigley from Monday through Wednesday can also take home a Hall of Famer's autograph for a charitable cause. Fergie Jenkins will sign autographs from 10:30 a.m. to 1 p.m. CT at the Cubs Store across from the ballpark on Monday and inside "Clark's Clubhouse" on Tuesday and Wednesday from 6 p.m. until the sixth inning to raise money for the Ron and Vicki Santo Diabetic Alert Dog Foundation. Vicki Santo and Logan Burke, who was the first recipient of an alert dog from the foundation, will throw a ceremonial first pitch on Wednesday.

Cubs likely to finish '14 with six-man rotation

ST. LOUIS -- The Cubs want to take advantage of the final month to get a look at pitchers Felix Doubront and Jacob Turner, and will likely go to a six-man rotation, general manager Jed Hoyer said Friday.

Doubront, 26, will make his first start Saturday in the first game of the Cubs' day-night doubleheader against the Cardinals. He had started 10 games for the Red Sox before the Cubs acquired the left-hander on July 30 for a player to be named.

Turner, 23, made his first start for the Cubs on Wednesday and lasted 3 2/3 innings against the Reds. Chicago acquired him from Miami for two Minor League pitchers.

Hoyer said they want to insert Doubront and Turner in the rotation, and also lighten the innings for current starters Jake Arrieta and Travis Wood.

"It makes sense to get looks at guys and give guys innings and lessen the load on guys we have," Hoyer said.

Doubront has been on the disabled list with a left calf strain. Whoever the Cubs take off the 25-man roster to open a spot for Doubront can be added as the 26th man for the doubleheader.

Ruggiano done for season after ankle surgery

ST. LOUIS -- Cubs outfielder Justin Ruggiano is done for the season after undergoing surgical debridement on his left ankle, an arthroscopic procedure that removes dead or damaged tissue.

In his first season with the Cubs, Ruggiano batted .281 in 81 games with six home runs, 13 doubles and 28 RBIs. He was placed on the disabled list on Saturday, and had returned to Dallas to see a specialist, where he had the procedure done.

The Cubs had more encouraging news regarding outfielder Ryan Sweeney, who was headed to Arizona to begin a rehab assignment at the team's complex. Sweeney has been on the DL since Wednesday with a left hamstring strain.

Manny Ramirez, who was a player/coach at Triple-A Iowa, was placed on the Minor League team's disabled list with a knee injury. Cubs general manager Jed Hoyer said they were impressed with how Ramirez mentored the young players, particularly Jorge Soler and Javier Baez.

"We feel really good about the way that the entire experience went," Hoyer said. "He was outstanding in Iowa. People focus on Soler and Baez, but Kris Bryant, [Chris] Valaika, and the coaching staff sing his praises. I don't know what our relationship will be going forward. It's too early to speculate on that. I'm really happy for Manny. It seems like he's in a really good place."

Would Ramirez consider being a full-time hitting coach? Hoyer said the 42-year-old outfielder still wants to play.

"Until a guy is willing to admit he's done, it's hard to have those conversations [about coaching full time]," Hoyer said.

Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.