CHICAGO -- Pedro Alvarez stepped to the plate ready to strike in a big spot.
Once again, he delivered.
Alvarez hit a three-run homer to cap a five-run seventh inning and Jason Grilli retired Emilio Bonifacio on a bases-loaded grounder to end the game, giving the Pittsburgh Pirates a 5-4 victory over the Chicago Cubs on Thursday.
The Pirates trailed 4-0 heading into the seventh, but two big drives changed things.
Pinch hitter Travis Snider cut the deficit in half with a two-run homer off Brian Schlitter. Alvarez put Pittsburgh ahead with his three-run shot on the first pitch from James Russell (0-1), his third homer in two games and fifth this season.
"Just trying to be ready from pitch No. 1, ready to compete, and sometimes that first pitch is the best one you see and just trying to be ready to hit as soon as I step in the box," Alvarez said.
Chicago threatened in the bottom of the ninth before Grilli retired Bonifacio on a grounder to first. Pittsburgh took two of three at Wrigley Field.
That gave the Pirates their third series win -- the most for them to start the season since the 1992 team took its first six.
Gerrit Cole (2-0) struck out 10 in six innings. He also allowed four runs, three of them earned.
Grilli gave up a leadoff walk to pinch hitter Ryan Sweeney and a single to Starlin Castro, putting runners on first and second. Grilli then struck out Luis Valbuena and Welington Castillo before Darwin Barney walked to load the bases.
Bonifacio, who came into the game with a .500 average after going 19-for-38, ended it with that grounder to first baseman Travis Ishikawa, giving Grilli his third save in four chances.
Chicago's Travis Wood sailed through six-plus innings, allowing four hits, striking out nine and walking three. He left to cheers with a four-run lead after Neil Walker led off the seventh with a double.
Snider, batting for Clint Barmes, then drove a two-run homer to the shrubs in center off Schlitter, cutting it to 4-2. Schlitter also gave up a single to Starling Marte and walked Andrew McCutchen with two out before Alvarez drove the first pitch from Russell off the roof of a party suite beyond the bushes in center.
"It's tough, especially as well as Woody pitched," Russell said. "You never want to mess up (an outing) that he had. It's one of those deals. It's why we play the game. It happens. We live to see another day."
With a 1-0 lead going into the fourth, the Cubs took advantage of a wild pitch while scoring three more runs.
The lead grew to 4-0 when Castro scored on Castillo's two-out single. The throw from Marte in left beat the runner by several strides, but plate umpire Mark Carlson called him safe.
Carlson told a pool reporter that Castro's foot touched the plate before catcher Tony Sanchez had control of the ball. He also said, "If he has the ball securely, he would have been able to block the plate."
Manager Clint Hurdle came out of the dugout to discuss the play, but obstruction "never came up."
He also chose not to challenge but would not say why.
"If I give you any other answer, we got 10 more questions," Hurdle said.
The Pirates said top pitching prospect Jameson Taillon had Tommy John surgery on his right elbow Wednesday. He is expected to miss 12 to 18 months. ... The Cubs open a three-game series at St. Louis on Friday, and manager Rick Renteria was asked whether he sees the Cardinals as a model for what Chicago is trying to do. "It's hard to argue with a club, an organization, that's had success over the years," he said. "You've got to see what it is that they do and don't do. You take things from every organization in baseball, but certainly, they've had a tremendous amount of success over the last few years -- and over their existence."