Dusty Baker is returning to Wrigley Field having led the Washington Nationals to the verge of the best start in franchise history.
His former Chicago Cubs have raced to their best in more than a century.
The NL's two leading teams will open a four-game series Thursday night, and Washington's Joe Ross will try to provide another stellar outing when he faces a formidable lineup.
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In his first season at the helm, Baker has the Nationals at 19-8 for their best start since 1979, when they were the Montreal Expos. That team lost its 28th game.
Washington bounced back from having a four-game win streak snapped in emphatic fashion Wednesday, routing Kansas City 13-2. Daniel Murphy provided four hits, boosting his average .398, and drove in three runs.
Bryce Harper chipped in his 10th homer and first in nine games.
The Nationals are 5-1 on a 10-game road trip and are 11-4 away from home. They'll collide with a Cubs team off to its best 26-game start since going 22-4 in 1907.
Chicago (20-6) completed a three-game sweep in Pittsburgh with a 6-2 victory Wednesday, moving six games ahead of the second-place Pirates in the NL Central.
Ben Zobrist hit a three-run homer, giving him 12 of his 16 RBIs in his last 10 games. Anthony Rizzo stayed in the thick of the NL longball race with his ninth and finished 7 for 14 with six extra-base hits in the series.
The Cubs boast easily the majors' best run differential at plus-93 (159-66). The Nationals are at plus-50 (120-70).
"Offensively we keep having good at-bats over the course of the game and then have a chance to work people down by the end. That's pretty much been the roadmap to this point," manager Joe Maddon said.
Ross (3-0, 0.79 ERA) will attempt to stifle that Chicago lineup after yielding one run in six innings of a 6-1 win in St. Louis on Saturday. The 22-year-old right-hander has yielded two runs through 22 2-3 innings, and opponents are batting .195 against him.
"There's nothing finer than a young pitcher that gets confidence and knows that he belongs here. And he certainly has confidence," Baker told MLB's official website. "He's not intimidated by being in the big leagues."
Ross' only game against the Cubs came in his major league debut June 6, giving up three runs in five innings of a 4-2 loss.
While Ross might not have to face Jason Heyward (sore wrist), who remains day to day, Ben Revere could return after being sidelined since straining his right oblique in his Washington debut April 4.
Revere has hit better than .300 in each of the last three seasons and has stolen 176 bases in his past five, fourth-most in the majors.
"(Revere) is our igniter. That's why we brought him here," Baker said. "We will add another dimension to our team and our offense to go along with what we have now."
A well-rested Kyle Hendricks (1-2, 3.91) will seek to build on a solid performance. The right-hander hasn't pitched since April 26, when he yielded one run, two hits and one walk in five innings but did not get a decision in a 4-3 win over Milwaukee.
Hendricks, skipped in the rotation following a pair of rainouts, was 0-2 with a 5.56 ERA in his prior two starts. He is 1-0 with a 2.25 ERA in two starts against Washington, both last season.
Baker was 61-38 versus the Cubs in his six seasons in Cincinnati after leaving Chicago in 2006, with a portion of those matchups against a rebuilding organization.