PHOENIX -- Coming off a rough series in New York having dropped three of four to the Mets, it turns out all the D-backs needed was another matchup against the Cubs to get them back on the winning track. 

Lourdes Gurriel Jr. and Alek Thomas each hit three-run homers off Justin Steele as the D-backs won, 6-4. It was the fourth win in five games for Arizona over the Cubs after taking three of four in Wrigley Field last weekend. 

• Games remaining (13): vs. CHC (2), vs. SF (2), at NYY (3), at CWS (3), vs. HOU (3)
• Standings update: The D-backs (77-72) have the same record as the Reds (77-72), but Cincinnati (which also won Friday) holds the tiebreaker and the third Wild Card spot. Arizona is a half-game ahead of the Marlins (76-72). The Giants (75-72) are a game back. The D-backs do not hold the tiebreaker against the Reds or Marlins and they are 5-6 vs. San Francisco this season, with an upcoming two-game set which will determine the tiebreaker. The D-backs trail the Cubs by 1 1/2 games for the No. 2 spot, and clinched the tiebreaker over Chicago with Friday's win.

Here’s a deeper look at three key moments from the series-opening victory:

Gurriel’s homer was huge

After the bats slumped in New York, the D-backs were desperate for any spark that could ignite them.

Gurriel provided just that with two outs in the first inning, when he hit a first-pitch slider from the Cubs' Justin Steele into the left-field bleachers for a 3-0 lead. You could almost hear the collective sigh of relief in the Arizona dugout as Gurriel circled the bases.

“I think it gave us a chance to breathe a little bit,” Thomas said.

“We made a statement with a big three-run homer in the bottom of the first inning,” D-backs manager Torey Lovullo said. “It let us take a big, big exhale.”

“I think Guriel hitting that three-run homer early on was definitely a momentum shifter,” Pfaadt said.

Pfaadt pitched very well

Pfaadt faced the Cubs last weekend in Chicago, and in an attempt to get him some better matchups Lovullo went with an opener before bringing Pfaadt in to start the third inning, after which he allowed four runs over six innings.

On Friday, though, Pfaadt started the game and held the Cubs to just four hits and a walk, and no runs, over 5 1/3 innings.

“He was just pounding the zone,” Lovullo said. “It looked like he had a good sinker, four-seamer with a sweeper combination and just got a lot of big swing-and-miss moments in some very key at bats. And for me it just looked like he was in total control throughout the course of his outing.”

“I thought he filled up the strike zone,” Cubs manager David Ross said of Pfaadt. “It's a lot easier to pitch with a three-run lead, coming right at you, throwing strikes, getting the secondary for strikes. Then he threw some nice 3-2 breaking balls. But I don't think we got a real good sense of what he was trying to do to us at any time.”

The Thomas homer proved big

Before he went to the plate to face Steele for the third time, Thomas got some guidance from hitting coach Joe Mather.

“Joe Mather said, ‘You were on the heater, so you're probably not going to get another heater early in the count, so be prepared for a slider,’” Thomas said. “And thankfully, I did get a slider, and it was in a good spot.”

The three-run homer pushed the score to 6-0, and while it was nice to have that extra cushion, it didn’t seem to be crucial at the time.

But it loomed very large after the Cubs rallied for four runs in the ninth inning off the Arizona bullpen, mashing a trio of homers against Kyle Nelson and Paul Sewald, before Sewald shut the door.

“Pretty sweet feeling being able to help out the team and increase the lead,” Thomas said.