Fukudome entered Thursday's game against the Detroit Tigers batting .154 in June with 20 strikeouts in 18 games. His on-base percentage is .267; it was .461 in April when he hit .338.
Sasaki, who was Fukudome's coach with the Chunichi Dragons and with whom he worked this winter, is expected back in July when the Cubs are in Philadelphia. Until then, the Cubs have to wait and hope Fukudome figures things out.
"I don't know what to do," Piniella said Thursday. "I can write his name in the lineup, give him an opportunity to play. I can sit him. That's an option, too.
"I've moved him around in the lineup. He's got to swing the bat. Last night, he got a base hit to left field. He's got to be able to use the whole field. I don't know what else to do. I can write his name in the lineup but he's got to do it."
The Cubs welcome any input to get Fukudome back to the form that won a batting title in Japan. Sasaki was his coach then.
"I'm all for it," Piniella said about Sasaki's return. "We can bring in the whole Japanese hitting academy if it'll help him hit. It doesn't matter to me."
Last season, Fukudome got off to a good start, and finished with a .257 average that included .217 in the second half.
"He got off to a good start last year," Piniella said. "The amazing thing about the big leagues is that you have to have consistency. Consistency is the most important thing here. You win with consistency. You can't play great for a few days and then [bad] for a few days. The more consistent you are as a team and a player, the more you'll be able to win.
"We have confidence he's going to hit, but he's got to do it. We can't do it for him."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.