On Sunday, Giles was efficient, throwing nine of his 11 pitches for strikes.
"It was really good; I was really comfortable out there," Giles said. "All I did was just attack hitters and be aggressive."
He recorded his first strikeout against Nate Schierholtz on an 88-m.p.h. slider.
"The slider is going to be very important," he said. "That is what will keep them off my fastball."
On this day, the Cubs couldn't keep up with the fastball. Giles noticed the fans' reaction.
"It gets me pretty pumped," he said. "As long as fans are getting pumped up anyway to help us get back in the game, I think it will help us."
Manager Ryne Sandberg said he would continue to pick his spots in using Giles.
"Let him build some momentum and gain confidence," Sandberg said. "Being his second outing, he showed really good progress and [had] a real good outing today, so that's good for him."
Jimmy Rollins has a 10-game hitting streak, with one hit in 10 consecutive games. A day after setting the Phillies' career hits record, he went 1 for 4, giving him 2,236 hits. During his streak, Rollins is 10 for 38 (.263).
Losing pitcher A.J. Burnett struck out four in eight innings and moved into sole possession of 50th place on the career strikeouts list. He has 2,254 strikeouts and needs 17 to pass Lefty Grove (2,270) for 49th place.
Burnett did not walk a batter for the second time this season. The first time came when he also pitched a season-high eight innings, in a 2-0 win at Arizona on April 27.