PHILADELPHIA (Reuters) - The Philadelphia Phillies held off a spirited rally to defeat the Chicago Cubs 7-5 at Citizens Bank Park on Friday.

Philadelphia built a 7-0 lead on the strength of seven strong innings from starter Roy Halladay and a grand slam by Placido Polanco in the seventh inning, but nearly let the game slip away in the eighth inning.

"I tried to be aggressive," said Polanco. "He (Zambrano) is a great pitcher and may only give you one pitch to hit in the at-bat."

Halladay allowed six hits while striking out nine batters and did not give up a walk in seven scoreless innings to earn his league leading ninth win.

"I thought where we were at, we could get six outs," Phillies manager Charlie Manuel said. "I thought we had the game in control."

In stark contrast to Halladay's brilliance, three Phillies relievers combined to allow five runs on three hits and three walks in the eighth inning alone before Michael Stutes induced a fly ball out by Kosuke Fukudome with two men on to end the threat.

Stutes gave up a lead-off walk to Darwin Barney in the ninth inning but struck out Starlin Castro and Phillies catcher Carlos Ruiz threw out Barney attempting to steal second base for a double play. Antonio Bastardo closed out the game with a strikeout for his second save of the season.

Cubs starter Carlos Zambrano allowed seven runs on seven hits and seven walks while striking out five in over six innings, and left the game after serving up the grand slam to Polanco.

Shane Victorino scored Philadelphia's first run in the first inning and Domonic Brown extended the lead to 3-0 with a two-run homer in the second inning.

(Reporting by Mike Mouat in Windsor, Ontario. Editing by Ian Ransom)