CHICAGO (AP) -- Kerry Wood's right shoulder is bothering him again.
Pitching in 42-degree weather, Wood (1-1) said his shoulder was stiff before the game, but he loosened up and struck out a season-high eight in five innings. He was lifted after only 76 pitches because of discomfort that felt similar to what bothered him in spring training.
The right-hander started just three games this spring because of bursitis in his shoulder.
"I've got some treatment to do," Wood said. "It's not an injury of any kind where I'm going to miss time, hopefully."
But the Cubs weren't sure if he would miss his next start.
"It all depends on how it calms down between now and then," manager Dusty Baker said.
Wood said the weather made it tough on his shoulder.
"It was a little cranky today," he said. "This was the coldest day I've pitched in so far this year. We kind of made the decision it was enough and get ready for the next one."
Wood's breaking ball looked sharp. He gave up two runs, three hits and three walks.
"He was throwing the ball good," Baker said. "It was a matter of putting him in a designated amount of innings."
The Cubs trailed 2-0 before they got to starter Dave Williams (1-2) in the fourth, scoring four runs on a pair of homers.
Perez homered to left on a 1-0 pitch leading off the inning, and Derrek Lee and Aramis Ramirez followed with solid singles. Williams
struck out Jason Dubois, but Burnitz connected for a long homer to right.
"I was out there trying to throw heaters and that's pretty much the ballgame," Williams said. "In the back of my mind, I knew I had to throw another curveball to Burnitz, but I just didn't and he got me."
Williams retired eight in a row after Burnitz's home run. He gave up four runs and five hits in six innings, striking out five.
Burnitz was 0-for-9 before hitting his third home run of the season and just 4-of-24 against left-handers, including a strikeout in the second.
"He made a mistake to a guy hitting .174 against left-handers," Pirates manager Lloyd McClendon said. "You just can't make that pitch in that situation."
Perez, who started at second base, added an RBI single in the eighth. He's 8-for-11 in his last three games and is hitting .396. After injuries to second baseman Todd Walker and shortstop Nomar Garciaparra, he's become an invaluable part of the team.
"I think [cold weather] makes me a better hitter," Perez said. "Because I know I have to hit the ball on the sweet spot of the
bat. Otherwise, I might break my hand."
Fox earned his sixth career save and first since April 25, 2003, with Boston. Baker said because of Fox's injury history, he probably wouldn't pitch him more than two days in a row.
"All I care about is going out there to win," Fox said. "You've got to go out there and get your three outs, or an out, whatever you're called on to do. Today was my day to close and we'll see what happens tomorrow."
With LaTroy Hawkins struggling, Baker said he would have to use his relievers based on situations and matchups for the time being.
"[Hawkins] is going to have some opportunities to close some games," Baker said. "Probably most of the time [he'll be used] in the eighth."
Williams was starting for Josh Fogg, bumped from his scheduled start because of an inner ear infection. Fogg will start Wednesday against Houston.
The Pirates, who had won consecutive games for the first time this season, took the lead in the second inning on Freddy Sanchez's two-run double with two outs.
Wood then struck out six of his next 12 batters. He walked the leadoff batter in each of the first three innings, but none of them scored.
The Pirates stranded two runners in the sixth and Sanchez at third in the seventh. They left seven runners on for the game.
"We certainly had some opportunities to try and deliver a knockout punch, so to speak," McClendon said. "We just couldn't get the hit when we needed it."
Garciaparra was walking around the Cubs' clubhouse Sunday, a good sign after rupturing a tendon in his groin last week. He isn't sure whether he will need surgery. "I'm getting evaluated again in the next couple days," Garciaparra said. "As long as everything's consistent, we'll know to make the right decision." ... Joe Montana threw out the first pitch and mingled in the Cubs' clubhouse and dugout before the game. ... Cubs shortstop Ronny Cedeno made his first major-league start and went 0-for-3.