PITTSBURGH — Pirates manager Clint Hurdle was succinct with his assessment after getting swept by the Chicago Cubs.

“We just got out-executed for three days in a row,” Hurdle said.

Ben Zobrist hit a three-run home run, Anthony Rizzo also connected and Jon Lester worked out of a pair of jams to lead the NL Central-leading Cubs over the second-place Pirates 6-2 Wednesday for a three-game sweep.

With its seventh win in eight games, Chicago improved to a major league-best 20-6. The Cubs have won seven straight road games and completed their first sweep in Pittsburgh since Sept. 7-9, 2012. They lead the division by six games.

“We had our chances but we didn’t capitalize on them,” Pirates second baseman Josh Harrison said. “It’s disappointing to get swept but we’re good about getting past things. We came in, took a shower and now we’re moving on.”

Zobrist’s third-inning homer put Chicago ahead after center fielder Andrew McCutchen dropped Rizzo’s two-out liner for an error.

Lester (3-1) scattered eight hits in 5 2/3 scoreless innings, struck out five and walked two. The left-hander has allowed one run or none in five of six starts this season.

Pittsburgh loaded the bases in the fourth and put runners on first and second in the fifth — both times with no outs. The Pirates have lost four straight following a six-game winning streak.

“It says a lot about pitch execution because Johnny got in some jams and was able to pitch out of it, which was really nice to see,” Cubs catcher David Ross said. “He’s done that a couple times here lately.”

Rizzo doubled and scored on Javier Baez’s fifth-inning double and hit his ninth home run of the season in the seventh off Ryan Vogelsong. He had three hits, scored three times and finished the series with five doubles and the home run.

Baez also had three of the Cubs’ 12 hits and drove in the game’s final run with an RBI forceout in the ninth. Addison Russell added two hits and Kris Bryant extended his hitting streak to 10 games.

Pinch-hitter Matt Joyce had a two-run homer in the seventh against Adam Warren. Three of his four home runs have come as a pinch hitter.

Juan Nicasio (3-3) had won his first three home starts after being signed as a free agent, allowed four runs - one earned - eight hits and three walks in 4 1/3 innings.

“They have a good-hitting team and when I got to two strikes and threw my breaking ball they wouldn’t swing at it,” Nicasio said. “Sometimes you don’t have a good day.”

Pittsburgh got two hits each from McCutchen, David Freese and Harrison. McCutchen had gone 2 for 19 in his previous five games.

Red-hot Rizzo

Rizzo is hitting .362 (17 for 47) with 16 RBIs in his last 12 games after hitting .163 in his first 14. He also is batting .442 (23 for 52) in his last 13 regular-season games at Pittsburgh with nine doubles and nine RBIs.

Trainer’s room

Cubs: RF Jason Heyward (sore right wrist) did not start for a third straight game but Maddon is optimistic he might play Thursday.

Pirates: C Elias Diaz underwent surgery Tuesday to debride his right elbow, and the rookie is expected to be out until mid-July. He made his major league debut last September with two pinch-hitting appearances.