When the Mets head north at the end of the month, they play the Cardinals, Braves and Phillies in 14 of their first 19 games. Things could go south very quickly.

Last April was different; facing Washington, Florida and Milwaukee to open the season, the Mets went 11-2 on their warm-up jog before running roughshod over most of the National League.

But before the 2006 Mets, the 1995 Indians were the last team to be a league’s only 90-plus winner ‘ last season’s disparity was a rare occasion. The Mets will not be the NL’s only 90-win team in 2007. After keeping their roster largely unchanged this off-season, they might not even be the NL East’s.

And they might not even reach the 90-win plateau at all. Betting Web site Bodog.com has the over-under on the Mets’ win total this season at 89 1/2.

But if the Mets do manage to return as one of the league’s elite, it’ll be after taking it to their biggest rivals before the snow melts in April.

They will have to go through St. Louis and watch the Cardinals ‘ who finished 2006 with fewer wins after winning the World Series than the Mets had at the end of the regular season ‘ raise their championship banner and receive their World Series rings.

They will follow that by flying to Atlanta for the Braves’ home opener, where the Braves will have a chip on their shoulders for the first time in a decade-and-a-half after being dethroned as NL East champions last season, and a new bullpen to boot.

And it’ll be after the Mets leave Georgia and return to Shea for their own home opener to the pleasant noise of Jimmy Rollins’ and Brett Myers’ trash-talking, which might just be enough to drown out the noise from LaGuardia.

Pennants are not won only in September.

St. Louis, Atlanta and Philadelphia are not just the Mets’ rivals in storyline, they’re the best teams the NL has to offer ‘ the Cubs, Dodgers and dark horses aside. April will be a trial by fire, which could be a good thing: the Mets will be able to assess early on what needs fixing.

Omar Minaya and Willie Randolph can see if the front-end of the rotation is too old, if the back-end needs some innings in New Orleans or if Jose Valentin and Shawn Green are washed up. And it may mean that Valentin can’t hit .136 in April again and keep a roster spot.

But a trial by fire also has its downside: the Mets could fall behind quickly. There would be time to dig out of any hole, but not necessarily the means or the personnel; the Mets have the NL’s worst spring training record of 6-14. Sure, it’s just March. But in two weeks, it’ll just be April.