Outfielder Reed Johnson was placed on the 15-day disabled list, retroactive to June 18, with lower back spasms, and first baseman Micah Hoffpauir was optioned to Triple-A Iowa to make room for Ward and Marshall.
Ward returned from a bulging disc in his lower back and hip problems that have kept him out since May 14. He made stops at the Cubs' Spring Training facility in Mesa, Ariz., and a three-game rehab stint at Iowa over the weekend. Ward, who hit .500 (5-for-10) in Triple-A, arrived in Chicago on Tuesday morning and deemed himself fit for action.
"I was real rusty the first day of batting practice after about a month," Ward said of his rehab assignment. "I dribbled the first eight balls. It quickly came back. I had a really good game yesterday [for Iowa]. I feel pretty good. My leg is fine. My back is fine. I'm ready."
Ward was activated after an encouraging session of batting practice and fielding ground balls before the game. Manager Lou Piniella has said Ward is a prime candidate to be his designated hitter when the Cubs visit the White Sox this weekend.
Johnson's back problems flared in Tampa Bay last week, and he isn't expected to miss more than the 15 days. He'll be eligible to be activated on July 3, which is the Cubs' last game in San Francisco.
"It's already been a week, so why rush this thing for a few days?" Piniella said. "I think everybody's comfortable with the fact that when it's his turn to come off the DL, he'll be able to."
Johnson said he has mapped out his recovery, too.
"I feel good," he said. "I don't feel it will take me the full seven, eight days to be where I want to be, but at the same time it's the better thing to do than try to run me out there right now and maybe lose me for six weeks."
Johnson, who underwent back surgery last year, felt a tug in his back after he laid down a bunt in the ninth inning at Tampa Bay on June 17.
"Diving and doing all that stuff never bothered me," Johnson said. "I hurt it coming out of the box. It might change the way I train."
He will place more emphasis on his core work now, and said Kosuke Fukudome is a good example of someone who focuses on that.
"Upper body is overrated," Johnson said. "It's good for when you go to the beach."
Hoffpauir batted .400 (14-for-35) in his two Major League stints, totaling 18 games this season. He subbed for Ward as Piniella's go-to left-handed pinch-hitter.
Marshall takes the injured Carlos Zambrano's spot in the rotation. The left-hander compiled 4.15 ERA in 13 relief appearances for the Cubs in April and May.
Piniella was asked if Marshall felt ready for his first Major League start of the season.
"If he doesn't, it's too late," Piniella joked before Tuesday's game. "He's got the ball. He'll go out and pitch well. He's had quite a few starts in Triple-A, and we've stretched him out as well as he can be. It's just a matter of going out there and executing."
Nick Zaccardi is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.