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8/27/2014 7:18 P.M. ET

Part of rally, Epstein lauds JRW, organizers

CINCINNATI -- Who's the best baseball team in the city of Chicago? It could be the Jackie Robinson West team, which won the U.S. title in the Little League World Series and was celebrated with a parade in Chicago on Wednesday.

"Anyone who watched that team play for an inning or two on TV probably couldn't help but watch the rest of the tournament," said Cubs president of baseball operations Theo Epstein, who took part in the pep rally. "There was a magnetic quality to that team.

"Probably the best thing to happen to the whole city of Chicago this summer from a baseball standpoint was put together by 13 12-year-old kids from the South Side of Chicago," he said. "It's good for the city, the country and the game of baseball."

The Cubs will have some of the Little Leaguers at Wrigley Field during the next homestand. The date has not been set yet.

"At industry meetings and in front offices around the game, people ask how we can get young people playing the game of baseball," Epstein said. "There's nothing that a bunch of suits in a board room can do that will be as powerful as what those 12-year-old kids did to demonstrate how compelling the game of baseball can be. They made baseball cool again for young kids."

He complimented the Jackie Robinson West organizers, who have been proactive in terms of finding kids, selling them on the game of baseball, and getting them to practice and off the streets so they can learn about sportsmanship, hard work and discipline.

"We can all go to school on how they built their program," he said.

Tight lower back keeps Rizzo out of starting lineup

CINCINNATI -- Cubs first baseman Anthony Rizzo did not start Wednesday because of lower back tightness, which had forced him out of Tuesday's game.

Manager Rick Renteria said Rizzo would receive treatment Wednesday, and he could be back in the lineup Thursday.

Rizzo, who hit his 30th home run on Tuesday in the Cubs' 3-0 win over the Reds, has started 129 of the team's 132 games.

He is the first Cubs left-handed hitter to reach 30 home runs in a season since Fred McGriff belted 30 in 2002. A Cubs left-handed hitter has totaled 30 home runs in a season 11 times, including five by Hall of Famer Billy Williams. Williams owns the franchise record for most home runs by a lefty, hitting 42 in 1970.

Chris Valaika started at first base Wednesday for the Cubs.

Sweeney, Ruggiano to DL; Watkins recalled

CINCINNATI -- The Cubs placed outfielders Ryan Sweeney and Justin Ruggiano on the disabled list, and the team was still testing the two players to determine if either injury is season ending.

Sweeney was placed on the 15-day disabled list with a left hamstring strain on Wednesday. Ruggiano was put on the 15-day DL, retroactive to Saturday, because of left ankle inflammation.

Manager Rick Renteria said both players were undergoing tests to determine the extent of their injuries.

The Cubs recalled Logan Watkins and Jorge Soler from Triple-A Iowa to take their spots on the roster.

Sweeney, who was batting .251, had to leave Tuesday's game after one at-bat because of the injury. He said he injured it running to first base in the second inning. Sweeney missed time in June because of a right hamstring strain.

Ruggiano was batting .323 in his last 44 games with nine doubles, four homers and 20 RBIs. He said his ankle has been bothering him for the last two weeks, and he has not started a game since last Thursday.

Extra bases

• Cubs No. 3 prospect Addison Russell played last season in the Arizona Fall League, but Chicago wants the shortstop to do so again, starting Oct. 7. Why?

"It's all about the at-bats for Russell," Epstein said.

Russell missed time earlier this season because of a hamstring injury.

• Felix Doubront is expected to start the first game of Saturday's doubleheader against the Cardinals with Tsuyoshi Wada starting the second game. The day-night doubleheader is a makeup of a May 14 game in St. Louis.

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.