DENVER -- The Padres began a daunting stretch of 18 games in 18 days on Friday night -- and it’s hard to envision a more difficult place to do so. Aside from the obvious challenges that come with playing baseball games at Coors Field, San Diego has struggled plenty against the Rockies this season.

Those struggles continued as the red-hot Padres dropped a 7-3 decision in their series opener in Colorado. Matt Waldron was roughed up for all seven of those runs, including four in the first inning. That was too big a hole to overcome, particularly on a night when the Padres’ offense hit into four double plays.

“We've just got to focus day by day,” second baseman Xander Bogaerts said. “Don't worry about that tough stretch. Try to monitor your work and be smart about it. We've got to look forward to coming in here tomorrow and try to win this game tomorrow, because obviously we didn't start it off the way we wanted.”

The surest hint that the Padres were embarking on that tough stretch came in the top of the sixth inning. A sweat-soaked Waldron had surrendered six runs and thrown 92 pitches when he emerged from the dugout. The Padres needed him, and although Waldron surrendered another run, he took down an additional two outs.

“An important couple outs there,” Padres manager Mike Shildt said. “Overall, he got better as the game goes. Which is what Matty pretty much does.”

Indeed, Waldron has made a habit of starting slow. After Friday, Waldron’s first-inning ERA ballooned to an even 9.00. He has allowed 25 first-inning runs in his 25 starts. In all other innings, he’s posted a 3.42 ERA.

Even Waldron isn’t sure whether that’s due to the fickle nature of the knuckleball. It’s possible it just takes a bit of time to figure out the way the pitch is moving that night.

“It hurts to let my teammates down, especially so early, to give the momentum away,” Waldron said. “I've got to wear it. I'll get real with whatever work I need to do and give myself the best chance.”

The Padres threatened all night, putting plenty of traffic on the bases. Consistently, they were undone by the double play. Before Waldron even took the mound, Bogaerts bounced into an inning-ending double play with the bases loaded in the top of the first. Manny Machado, Ha-Seong Kim and Jurickson Profar followed with double plays of their own.

In his next at-bat after his first-inning double play, Bogaerts launched the second-longest home run of his Padres tenure deep into the left-field seats, a Statcast-projected 447 feet.

“I don't remember the last time I hit a ball like that,” Bogaerts said. “Felt good. Wish I got that in the first at-bat. It hurts, man, a bases-loaded double play. Got to come in here tomorrow, try to win the game tomorrow.”

The Padres will have to do exactly that if they’d like to set a franchise record by winning a ninth straight series. They remain amidst one of the best stretches in franchise history. Even with the loss Friday, they've won 19 of 23 games, tying a club record.

But the challenge at hand is a formidable one -- 18 games in 18 days, starting with the series at Coors Field. If the Padres can withstand it, still alive in a tight National League West race, still firmly in postseason contention... well, it'll be September then. The Dog Days will be over. The playoff race will be well and truly on.

First, they have to get there. On Friday, there would be no comeback for these comeback-happy Padres.

“We have a good situation early on, then a double play erased the first, basically,” Shildt said. “Had some other traffic next several innings, over the course of the game. Just couldn’t get that proverbial big hit to break it open or to get back in it.”

With the loss, the Padres fell three games behind the Dodgers in the NL West race, while staying level with the D-backs, who lost in Tampa Bay. The Padres have been adamant that their focus is only on themselves -- that they aren’t paying close attention to the day-to-day standings.

That’s not always easy.

“They have a big scoreboard out here in right field,” Bogaerts said. “So it's a little tough to not see it. But you try not to focus on that. Try to win the game on that day. We didn’t start off good today.”