PHOENIX, Ariz. -- Rookie Junior Lake hit his first major league homer and drove in three runs to power the Chicago Cubs to a 4-2 victory over the Arizona Diamondbacks.
Lake's two-run homer off Tyler Skaggs with no outs in the fifth inning gave the Cubs a 3-0 lead. Lake's RBI single in the ninth scored Darwin Barney with an insurance run.
Dioner Navarro hit a solo home run in the second for the Cubs.
Skaggs (2-2) took the loss for the Diamondbacks, who dropped out of first place in National League West combined with the Los Angeles Dodgers' win in Toronto. They held or shared the division's top spot since May 15. Arizona has lost four of its last five.
Chris Rusin (1-0) got the win after being a late substitute for Matt Garza, who was traded earlier Monday to the Texas Rangers for five minor league players. Kevin Gregg pitched the ninth for his 19th save.
Rusin appears to be the Cubs' go-to pitcher after trades. When Scott Feldman was dealt to Baltimore, Rusin stepped in but did not receive a decision in an eventual 8-7 loss to Oakland. With the trade of Garza to Texas Monday, Rusin again received the call to start, held the Diamondbacks scoreless until the sixth inning, and picked up his first win of the season.
After Navarro's solo blast gave the Cubs an early 1-0 lead in the second, Chicago added a pair in the fifth as Lake slammed a 2-0 pitch into the left-centerfield bleachers with Rusin on base.
Effective from the start, Rusin -- 8-7 at Triple A Iowa -- retired the first seven he faced. With one out in the third, Didi Gregarious slapped a single to right but was stranded when Skaggs struck out and A.J. Pollock fouled out to the catcher.
Through the first five innings, Rusin allowed two baserunners.
Rusin walked Cody Ross with one out in the fifth, but Ross was doubled up when right fielder Cole Gillespie grabbed Gerado Parra's sinking liner and fired to first baseman Anthony Rizzo for the double play.
Rusin pitched into the sixth and left with runners on first and second and no outs.
In that inning, the Diamondbacks managed to score both runners. First, Martin Prado's sacrifice fly scored Gregorius, and Paul Goldschmidt drove in his 79th run of the season with an infield single.
The Diamondbacks had an opportunity to take the lead, but could not capitalize in the seventh as pinch-hitter Eric Chavez flied to center field with the bases loaded and two outs.
In the eighth and with the tying run at third with two outs, Miguel Montero struck out to end that threat.
Earlier, plate umpire Doug Eddings made sure things did not get out of control. With a history of Arizona suspensions this season for hit batters, Eddings directly addressed the issue in the Cubs' half of the fourth inning. With two outs, Skaggs hit Navarro on the right knee with a pitch. Immediately after Navarro was hit, Eddings pointed to Skaggs and then pointed to both the Diamondbacks and Cubs dugouts. While Navarro was examined by Cubs trainer P.J. Mainville, Eddings went to mound and spoke directly with Skaggs.
NOTES: To make room on the roster for Skaggs, the Diamondbacks sent lefty Eury De La Rosa to Triple-A Reno. ... Rusin's previous appearance against the Diamondbacks was a 7-2 win at Arizona last Sept. 30. ... With a 4-for-5 night, Lake, recalled from Triple-A Iowa last Friday, is now 9 for 17.