NEW YORK -- One hundred and seventy-three days have passed since the start of the regular season. Entering Tuesday, the Mets had spent 170 of them in sole possession of first place in the National League East. They dipped into second for a single day in April, then another in early September.

Then, Tuesday, they fell into a tie for first with the Braves.

New York’s 6-4 loss to the Marlins at Citi Field, combined with Atlanta’s win over the Nationals, resulted in a situation that seemed unfathomable during the halcyon midsummer days in Queens: the Mets no longer have a hammerlock on the division, nor on the first-round postseason bye that the winner will assuredly receive. The NL East may come down to a three-game series this weekend in Atlanta, assuming Hurricane Ian allows those games to be played.

“I mean, this is fun,” said first baseman Pete Alonso, whose three-run homer gave the Mets temporary life in the fourth inning. “This is really, really fun being in a race like this. Every day is a chance to be great, so tomorrow’s another chance for us to be great. We just want to continue playing the great baseball we’ve been playing all year.”

Although the Mets are on a 101-win pace, they have not collected victories quite as consistently in September. Over the first third of the season, the Mets produced a .648 winning percentage. Over the second third, they posted a .630 mark. Since that time, the Mets have played .596 baseball -- still one of the better rates in the league, but not enough to keep pace with the Braves, who have been Major League Baseball’s best team since Aug. 9.

Atlanta has lost only a dozen games over that stretch, rarely suffering the type of fate the Mets did on Tuesday, when Carlos Carrasco allowed four runs in three innings to take the loss. Although much of the damage came on soft contact and a 339-foot JJ Bleday homer that barely snuck over the right-field fence, it was enough to sink the Mets to their third loss in five games (with the latter two coming against non-contenders). The good vibes from Alonso’s 40th homer lasted only until the fifth inning, when Trevor Williams allowed two additional runs in relief of Carrasco. From there, the comeback stalled.

In isolation, the defeat wasn’t enough to doom the Mets’ season, but it did ratchet up the challenge of their final seven games. For now, the Mets remain in control of their own destiny, provided they win at least a single game in Atlanta this weekend. (They hold a tiebreaker against the Braves by virtue of beating them nine times in 16 tries so far, so they only need to win one of their three remaining head-to-head games to retain that tiebreaker for the rest of the season. Unlike in years past, there will be no Game 163.)

“The biggest thing is if we win, that really takes care of ourselves,” Alonso said. “It really doesn’t matter what they do.”

There is, of course, significant incentive for the Mets to win the division. Doing so would allow them to skip straight to the NL Division Series, bypassing a potentially difficult matchup against a team such as the Padres, Phillies or Brewers in a best-of-three Wild Card Series. It would also allow them to avoid the juggernaut Dodgers until it comes time to play for the pennant.

But the Mets are also wary of looking too far in front of them. As talk of weather patterns in Georgia dominated the pregame hours at Citi Field, manager Buck Showalter continually steered the conversation back to the present day, the present time, the present situation. What mattered in the moment, Showalter said, was taking care of business against Pablo López and the Marlins.

New York’s inability to do so not only resulted in a loss, but offered Atlanta increased hope in the NL East.

The Mets chose instead to focus on the fact that the race is far from over.

“If you’d have asked me in February, who knows?” Showalter said of being tied with the Braves with seven games to go. “Some people might have taken you up on that. Our guys have worked hard to create an opportunity.”