The maturity of the Cubs showed early and late, and although the Marlins erased a three-run deficit early and pulled even at 4 in the third inning, they weren't able to execute late and were hurt by home runs from Ian Happ, Anthony Rizzo and Kyle Schwarber.
Happ homered on Jose Urena's first pitch. According to Stats, Happ is the first player to homer on the first pitch of the regular season since the Red Sox's Dwight Evans did so in 1986 against Hall of Fame inductee Jack Morris and the Tigers.
"The first inning was we were going to attack the hitters with fastballs," Urena said. "We knew they were going to be aggressive."
Urena said early jitters didn't get to him, but he allowed three runs in the frame, walking two and hitting three batters. According to Baseball Reference, Urena is the first starter to hit three batters on Opening Day since 1908, and he did it in one inning.
The Marlins tied it in the third inning off Jon Lester, capitalizing on Derek Dietrich's triple, and RBIs from Justin Bour, Garrett Cooper and Brian Anderson, who had two singles and two RBIs on the afternoon.
The Marlins were able to get Lester, making his seventh Opening Day start, out of the game after 3 1/3 innings.
"Don't expect to go out there and go through the motions," center fielder Lewis Brinson said. "Every game that we play, we expect to win. That may be far-fetched for some people, but it's just the way we're believing in this clubhouse and that's the attitude we're going to have."
MOMENTS THAT MATTERED Holding the line: After the Cubs reclaimed the lead, 5-4, in the fourth inning on Willson Contreras' two-out, RBI double, the Marlins had chances in the fourth and fifth innings. In each frame they had a runner on third with less than two outs, and twice reliever Steve Cishek, a former Marlin, turned Miami away. Cishek struck out Starlin Castro and retired Bour on a fly ball to left to strand Cameron Maybin on third in the fourth inning. In the fifth, with Cooper on third and Miguel Rojas (who doubled) on second, Cishek fanned Chad Wallach and got pinch-hitter Tomas Telis to pop to short.
"We get it to 4-4. I look at that fourth and fifth," Mattingly said. "We had a chance to tie it, and we weren't able to execute two innings in a row. Then they were able to add on."
Seventh inning stretched: The Marlins trailed, 5-4, in the seventh, and with one out, Schwarber homered off Tayron Guerrero, who struck out the first four batters he faced. Guerrero appeared to tire, and he exited after allowing two straight batters to reach. Drew Steckenrider entered and struck out Javier Baez. Steckenrider fell behind pinch-hitter LaStella, 3-0, and was able to work the count full. LaStella's two-run double broke open a four-run lead.
"Today we weren't able to stop them late," Mattingly said. "We don't execute a couple of innings and that really changed the game."
QUOTABLE "They have a high fan base, everybody knows that. But so do we. We've got to build ours. I heard plenty of Marlins fans out there. I'm glad for everybody that showed up today -- Cubs or Marlins fans. We'll get them out to the ballpark. All we have to do is win games." -- Brinson, on the energy in the ballpark
SOUND SMART WITH YOUR FRIENDS Dietrich was hit by a pitch in the ninth inning by Mike Montgomery. It's the 73rd time in Dietrich's career that's been struck, including two on Opening Day, the most in franchise history.
WHAT'S NEXT Caleb Smith, one of 12 Marlins to appear on an Opening Day roster for the first time, makes his debut with the Marlins on Friday for the 7:10 p.m. ET game at Marlins Park. Smith made nine appearances (two starts) for the Yankees last season, and in 18 2/3 innings, he had a 7.71 ERA. At two Minor League levels, the lefty was 9-1 with a 2.41 ERA.