The Cubs went on to beat the Padres 12-4 before 33,126 at Wrigley Field, led by another strong outing by Jason Marquis and home runs by Michael Barrett, Mark DeRosa and Cliff Floyd.
"I don't like to be hurt," he said. "It's sad for me. I like to play every day."
Soriano injured himself in the fifth while trying to get up and make a throw after a failed attempt to make a sliding catch of Clay Hensley's RBI single. Umpire Gary Cederstrom ruled Soriano trapped the ball, and trainer Mark O'Neal rushed out to the field when he saw Soriano grab the back of his leg.
"He strained it when he tried to throw the ball," Piniella said. "Outside of that, it was a really nice night for us."
Center fielder Felix Pie is hitting .444 at Triple-A Iowa, but general manager Jim Hendry was hesitant to call him up.
"I've never been a believer that you start making decisions after 10-11 games," Hendry said before Soriano was injured. "You play a little while. He's going to be a good player for a long time, and when it's the right time to bring him up, we're certainly going to act on it."
If Soriano has to be placed on the disabled list, Hendry may have no other option. The Cubs lacked outfield depth even before the injury, and fourth outfielder Ryan Theriot was at second because DeRosa was subbing for the injured Aramis Ramirez at third.
After Soriano left the game, Floyd came in to play left, while Jacque Jones moved to center, where he last played in 2005. Floyd finished with four RBIs, including a three-run homer.
The game of musical chairs in the outfield began when Piniella announced beforehand that Matt Murton would play right, with Jones moving to left. He also revealed he'd asked Soriano if he'd rather switch back to left, where he played last year for the Nationals.
"He feels very comfortable in center field," Piniella said. "What we want Soriano to do is hit and generate offense for us.
"I told him, 'Look, we'll move you. We want to make it as easy as possible for you to be comfortable at home plate. Take that load off.' He said, 'No, I feel good. I really do.'
"I haven't been displeased with his play at all. The only thing I say is we brought him in here to hit, and if center field is causing a problem, we want to eradicate that."
Soriano enjoyed the meeting but was adamant about remaining in center.
"My hitting is not because of that," he said. "I'm trying to do too much—new contract, new team, new city, a lot of expectations. But I try not to think about the money."
But it's hard not to think about the money when everyone keeps reminding you of it.
"When you say $136 million, that's a lot of money," he said. "I don't put that kind of pressure on myself.
"I want to put this team in good position, because last year they had a tough year and I don't think they want that happening with me here, especially knowing all the money they spent on players."
One of those players was Marquis, who earned his first win in a Cubs uniform. He held the Padres to one run and three hits in six innings. He also chipped in with two hits and two runs.