PHOENIX -- Brandon Webb won the duel in the desert.
Stephen Drew homered in the fourth off Chicago's Carlos Zambrano, pulled after six innings and only 85 pitches. Right after he left, Mark Reynolds homered on the fourth pitch from reliever Carlos Marmol to break a 1-all tie in the seventh.
Pinch-hitter Conor Jackson added a sacrifice fly, and the Diamondbacks received two hitless innings from their stingy bullpen.
Webb, the reigning NL Cy Young Award winner, allowed four hits and struck out nine over seven outstanding innings in his postseason debut. He walked three and hit a batter.
"The most exciting game so far," Webb said. "I was able to keep them off-balance. I had pretty good stuff tonight, great off-speed. Had some great strikeouts, key situations."
The Cubs, looking for their first World Series title in 99 years, had plenty of fan support -- even on the road. The Cubs hold spring training in nearby Mesa, and the valley is a popular retirement destination for Chicagoans.
In their first playoff appearance since losing Game 7 of the 2003 NL Championship Series to Florida, the Cubs managed little on offense. Alfonso Soriano, Jacque Jones, Aramis Ramirez and Cliff Floyd combined to go 0-for-16 with five strikeouts. Derrek Lee had a single but struck out three times.
Chicago twice got the leadoff batter to second with no outs early in the game but came away empty.
Zambrano gave up four hits, struck out eight and walked one before he was lifted by manager Lou Piniella in a questionable move.
"He probably could have gone another inning. We're bringing him back Sunday on three days' rest," Piniella said. "I took a shot with my bullpen. It didn't work today. They've done it all year."
Not this time. Planning for Game 4 might have cost the Cubs in Game 1.
The showdown between 18-game winners was as advertised, with Zambrano matching Webb pitch for pitch through six innings with the roof open at Chase Field on a 91-degree night.
"It was tough. I had to grind it out," Webb said. "Leadoff doubles a couple of times and just had to find a way to get it done."
With Zambrano gone, the Diamondbacks went ahead in the seventh. Reynolds hit Marmol's 2-1 pitch just over the left-field fence for a 2-1 lead. Chris Snyder walked and went to third on Augie Ojeda's single before Jackson came through while batting for Webb.
Marmol had allowed only two runs in 25 innings after Aug. 10 for a 0.72 ERA.
"His numbers are video-game numbers with the strikeouts and so forth," Diamondbacks manager Bob Melvin said. "Zambrano the same way."
Zambrano threw at least 87 pitches in all but one of his 34 regular-season starts. He reached 100 on 27 occasions.
Valverde, the NL saves leader with 47 in 54 opportunities this year, walked pinch-hitter Daryle Ward with two outs in the ninth to bring up Soriano, who bounced into a game-ending forceout that capped an 0-for-5 night.
The surprising Diamondbacks, the first team since the 1906 White Sox to have the league's best record and worst batting average, won in a fashion typical of their 90-win regular season. They received timely hits, good defense and terrific pitching.
The youngsters certainly weren't overwhelmed by the circumstances.
Drew isn't a rookie but is in his first full major league season. Reynolds was brought up from Double-A Mobile when third baseman Chad Tracy was injured hurt in May.
Chicago's run came on a bases-loaded infield single by Ryan Theriot with two outs in the sixth. Webb then struck out Zambrano, one of the game's best hitting pitchers.
Only three of the Diamondbacks' starters had faced Zambrano, and Drew was not among them. After striking out his first time up, he put Arizona ahead with a 432-foot drive over the pool in right-center.
Sandwiched around the big hit were two defensive gems by Drew at shortstop. He made a backhand stop of Geovany Soto's grounder to end the third, then he robbed Zambrano of an RBI with a leaping grab of a line drive in the fifth.
Zambrano doubled to start the third, but Webb fanned the top three hitters in the Cubs' lineup: Soriano, Jones and Lee.
- Muhammad Ali was in attendance and was introduced to the cheering crowd in the third.
- Jerry Colangelo, who brought major league baseball to Phoenix and was managing general partner before a messy change of ownership three years ago, threw out the ceremonial first pitch to a standing ovation. He threw to Randy Johnson, co-MVP of the 2001 World Series for Arizona. Johnson re-signed with Arizona but was sidelined with a back injury in early July and eventually underwent season-ending surgery.