PITTSBURGH -- Carlos Silva's stomach gave out early, and he lost his game legs trying to run the bases. His right arm? Nothing wrong with that.
Theriot was in a 7-for-46 slump before reaching base five times on a double, single, two walks and a force play that resulted from Silva's slowness. Geovany Soto added an RBI double against Dana Eveland (0-1) as the Cubs won for the second time in seven games overall.
Silva (8-0) gave up four hits, struck out five and walked one in his first start against Pittsburgh since 2003, all while pitching with an apparent case of the stomach flu that resulted in several hurried trips to the restroom.
"I tried to put that out of my mind," Silva said. "I just tried to go there and make my pitches."
He threw 102 of them, 75 for strikes, while becoming the first Cubs starter to go 8-0 since left-hander Ken Holtzman was 9-0 in 1967.
"He's been our best pitcher, let's be perfectly clear about that," manager Lou Piniella said. "He's stopped some losing streaks and he's been perfect for us."
Or, exactly what the Cubs haven't been in PNC Park, which they visited for the second time in six days because of a rain-out Wednesday. After starting 0-5 there, they avoided going winless in Pittsburgh over an entire season for the first time since the franchises initially met in 1887.
The announced crowd of 12,768 represented the tickets sold for Wednesday's game, but there were only 3,000 or so in the stands -- including 141 in the upper deck -- when the newly acquired Eveland threw his first pitch for Pittsburgh.
The crowd was so quiet at times, individual conversations could be heard in the stands. The atmosphere will be much different Tuesday when the Pirates oppose the much-hyped Stephen Strasburg before a sold-out ballpark in Washington.
"We're excited for that type of game," said manager John Russell, whose team has dropped eight of 11. "Some guys have talked about it, and our guys are anxious to play. It's going to be a full house. We'd like to spoil the opening debut of Strasburg, so it should be a good pickup for us."
Facing Silva wasn't.
"He kept the ball down and his sinker was working good," Garrett Jones said. "He didn't leave any balls over the heart of the plate for us to drive."
Jeff Baker had a sacrifice fly in the first and an RBI double in the third, when the Cubs might have added more runs if the 250-pound Silva had run the bases better. Silva singled on a fly ball that reached the right-field wall on one bounce, yet he held up at first.
"I didn't even try to go to second base, my legs weren't there," Silva said. "That's why I didn't want to do anything crazy."
Silva then was thrown out at second on Theriot's fly ball to short right field. Silva was forced to hold up until he determined whether the ball would be caught.
"I think I'd rather Carlos go out there and pitch the way he pitched then be killing himself on the bases," Theriot said.
Eveland, acquired on waivers from Toronto despite having a 16.39 ERA in his last three starts, gave up three runs and six hits over five innings, failing to record a strikeout.
General manager Neal Huntington called Eveland an upgrade over what the Pirates already have. But when Theriot doubled leading off the game, a fan in the nearly empty upper deck yelled at Eveland, "You'll fit right in here."
Marlon Byrd had run-scoring singles in his final two-bats and Derrek Lee added another in the ninth. Sean Marshall got the final five outs for his first save in two opportunities and the second of his career.
Pittsburgh hasn't swept any opponent at home in a season series lasting as many as six games since going 6-0 against the Giants in 1984. ... The Pirates are 7-2 against the Cubs, 16-32 against the rest of the NL. ... This is the eighth time in 124 seasons the Cubs have won only once in Pittsburgh.