CHICAGO -- Cubs manager Joe Maddon did not like how quiet things were in the dugout on Thursday out west in San Diego. There was a noticeable lack of intensity -- the kind helped along naturally in the raucous Wrigley Field environment -- so the manager wanted to get a message across to his players.

"We have to create our own energy," Maddon said. "And if you're going to be uptight about stuff, boys, we ain't playing much longer."

• Box score

On Friday afternoon, the energy was overflowing on the part of the Cubs, who reached a season high in runs by the fifth inning and kept the foot on the accelerator en route to a 17-8 rout of the Pirates in the opener of a crucial 10-game homestand. Anthony Rizzo launched a grand slam and Willson Contreras homered twice to lead a five-homer attack by the North Siders, who have 15 games left to punch their ticket to October.

With the win, the Cubs remained four games behind the National League Central-leading Cardinals, who routed the Brewers 10-0 on Friday night. Chicago is currently one game up on Milwaukee for the NL’s second Wild Card spot and 2.5 games back of the Wild Card-leading Nationals.

"There's a lot of things going on out there," Contreras said. "The race is pretty close, so a lot of people start saying things about the Cubs, about this, about that. We just have to go out there and have fun. You can't put those kind of things in your head, because they're going to get you and then you're going to start playing with pressure."

There was a wealth of offensive highlights from the rout:

• Rizzo's grand slam off Pirates lefty Steven Brault in the third inning marked the Cubs' single-season club-record 10th slam of the year. Rizzo, who has five grand slams in his career, has two of the slams in '19. Only the Astros (11) have more grand slams in the Majors this year.

• Rookie Nico Hoerner launched his first career homer in the first inning off Brault and the shortstop ended the day with four RBIs. Hoerner is the first Cubs player since at least 1908 to have multiple games with at least four RBIs within his first five career games.

• Nicholas Castellanos belted a two-run homer that gave him eight first-inning shots since joining the Cubs and 12 in the first this season. Only Eugenio Suarez (14) has more such blasts this year. Castellanos also notched his 50th double of '19 in the fifth. He is the first outfielder to have at least 25 homers and 50 doubles in a season since 2007 (Magglio Ordonez and Matt Holliday).

• The Cubs scored seven runs with two outs in the fifth, but only following a successful managerial challenge by Maddon. Kris Bryant was ruled out on a grounder to short, but the call was overturned after the replay and he was given an infield single. The Cubs then had six hits, one walk and one hit batsman in the next eight plate appearances.

• The five homers in the game moved the Cubs within two blasts of tying the franchise's single-season record for home runs (235 in 2004).

• Chicago leads the NL with 19 games this season with at least 10 runs scored.

While the Cubs pulled off a 4-1 win over the Padres on Thursday, that victory wrapped up a 3-5 road trip that helped the Brewers pull even with Chicago in the Wild Card standings heading into Friday. Back in the comforts of home, where the Cubs are 48-24 this year, Maddon said it was time for his team to take a more simplified approach.

"Just go out there and play the game," Maddon said prior to Friday's game. "I don't want over-preparation. I don't want more swings. I don't want more information. I don't want more audio, video, whatever-o. Just go play baseball right now. That's all our guys need to do. Play it hard. Before you walk out there, set your hair on fire and see what happens."

After the victory, Maddon laughed when asked if there was an appropriate amount of hair on fire against the Pirates.

"You know how bad hair smells when it's on fire? That dugout stunk today, man. It was great," Maddon said. "That's my point. That's what I was expecting out of our guys today, and we saw it. I want to believe that's going to continue."

The end result against the Pirates buried a top of the first that seemed to convey what Maddon was discussing during his pregame chat with reporters. The manager said his main concern with his players was that they have been playing tight. Then Chicago went out and made two errors on one play, helping Pittsburgh to a four-run opening frame against Jon Lester.

Those early missteps were erased by the five-run first, which was powered by homers from Castellanos, Contreras and Hoerner.

"Weirdly, I was expecting that response. I was," Maddon said. "I really thought, under the circumstances, the energy level was great. And then, to answer as quickly as we did ..."

"Oh man, that's huge," Lester agreed.

Lester also backed Maddon's assessment that the team has been playing too uptight of late.

"We're all trying too hard sometimes," Lester said. "I'm guilty of it. I think everybody in that clubhouse is guilty of it. You want to win the game before the game's even played. That's part of the grind of playing 162 games. You get into those funks sometimes. I think a game like today can help guys loosen up a little bit."