CHICAGO — When Chicago Cubs president Theo Epstein made his play for left-hander Jon Lester during the offseason, he must have had days like this in mind.

With the Cubs needing a solid start after playing 12 innings a day earlier, Lester lived up to his staff ace billing, striking out seven in seven innings as Chicago extended its winning streak to six games with a 4-1 victory over the Pittsburgh Pirates on Saturday afternoon at Wrigley Field.

"He was fabulous," Cubs manager Joe Maddon said. "That permitted everything to work for us today. We had the better pitching today and Jonny set that whole thing up. He was outstanding."

The Pirates managed nine hits off Lester (4-2), but he walked only one and had four of his strikeouts with runners in scoring position.

His biggest jam came in the seventh when he put runners at first and second with two outs but got center fielder Andrew McCutchen to look at a 94 mph fastball for strike three, ending the inning.

"That was a huge turning point in the game," Lester said. "They got some momentum, some infield hits, but to get out of there unscathed is huge, especially in a game that tight."

While Lester was dealing, the Cubs were trying to figure out ways to scrape out runs against left-hander Gerrit Cole, who came into the game having allowed eight earned runs in his last five starts.

Chicago didn't do much against Cole but made the most of what it got.

Third baseman Kris Bryant scored two runs and went 2-for-2 with two walks. He gave Lester an early lead, singling and scoring on a sacrifice fly by shortstop Starlin Castro in the first inning.

Pirates right fielder Sean Rodriguez tied the score with a solo home run to lead off the third, but the Cubs came back in the bottom of the inning and reclaimed the lead when Bryant scored on a fielder's choice by Castro.

Cole (5-2) was sharp in his six-inning effort, holding the Cubs to two runs, seven hits and a walk while striking out eight, including all three Chicago batters in the fourth.

It was the first road loss for Cole since Sept. 1.

"I wasn't executing with two strikes," Cole said. "It seemed I was getting the corners early in the counts and I was getting them late. ... The fastball was a good weapon today, but I kind of used at as a crutch. I kept throwing a lot of them. I couldn't locate it down."

The Cubs added insurance runs in the seventh. Second baseman Addison Russell scored on right-hander Arquimedes Caminero's wild pitch and first baseman Anthony Rizzo made it 4-1 with a sacrifice fly to center.

Pittsburgh threatened in the eighth, putting two on with nobody out against right-hander Brian Schlitter, but left-hander Phil Coke and right-hander Jason Motte left both runners stranded.

Left-hander Travis Wood worked a scoreless ninth for his first career save.

"It was set up for him and he got it done," Maddon said. "He got his first save and it was beautiful."

Chicago's six-game winning streak is its longest since 2011.

"It's a lot of fun. We're pitching pretty well," Bryant said. "Our offense has done some good things and we're playing good defense. Hopefully, we can keep it going."

NOTES: Chicago recalled RHP Brian Schlitter on Saturday from Triple-A Iowa, where he had no record and two saves in six innings. Schlitter was with the Cubs from April 10 to April 26 and went 0-2 with a 9.53 ERA in seven appearances. To make room for Schlitter on the roster, Chicago optioned OF Matt Szczur to Iowa. Szczur batted .262 (11-for-42) with two home runs, a triple and seven RBIs in seven games for the Cubs. ... Pittsburgh selected the contract of RHP Wilfredo Boscan and optioned IF/OF Steve Lombardozzi to Triple-A Indianapolis before the game Saturday. To make room for Boscan on the 40-man roster, the Pirates transferred RHP Brandon Cumpton from the 15-day to the 60-day disabled list. ... The Cubs are six games above .500 for the first time since Oct. 3, 2009. A six-game winning streak is the team's longest since winning seven in a row in August 2011.