DENVER — The biggest series of the season will open with a pitching matchup worthy of the occasion. The Mets will send Noah Syndergaard to the mound Tuesday against the first-place Nationals and Max Scherzer.

But what follows for the Mets hinges on what doctors have to say about lefthander Steven Matz, who is scheduled to be examined Monday.

The Mets are optimistic that Matz should be ready to rejoin the rotation after his scheduled start Saturday was scrubbed because of soreness in his left elbow and forearm. It’s conceivable that the lefty could start Thursday’s series finale.

If he does, the Mets would likely bump back Bartolo Colon, which would allow Matz, Syndergaard and Harvey to pitch in the three-game series. Colon is coming off his worst start and Harvey has suffered mediocre results.

“Until I get the report from the doctor, we’re just going to let it hang out there,” manager Terry Collins said of his rotation.

The Mets are carrying an extra bullpen arm, though they could revert to carrying a full bench this week.

advertisement | advertise on newsday

“We certainly need some extra players, for sure,” Collins said. “This is the National League, so your bench is really important.”

While Ty Kelly and T.J. Rivera have produced at Triple-A Las Vegas, the only name that has been seriously discussed internally for a promotion is infielder Matt Reynolds, who will give the Mets a backup shortstop with Wilmer Flores (hamstring strain) ineligible to come off the disabled list until May 27.

Reynolds, 25, is hitting just .240 in 32 games. But he is on the 40-man roster.

Mets videos

The Nationals will send Scherzer, Gio Gonzalez and Stephen Strasburg. Scherzer racked up 17 strikeouts while no-hitting the Mets last season. The righty is coming off his record-tying 20-strikeout game against the Tigers.

Rough series

Twice in three games against the Rockies, Michael Conforto misplayed balls in leftfield. Twice, it led directly to runs. They were examples that for all of Conforto’s offensive prowess, the 23-year-old’s play in left remains a work in progress.

Conforto took the wrong route to Carlos Gonzalez’s liner in the second inning, leading to a double. On Friday, he turned a Gerardo Parra single into a triple to the wall, after failing to cut it off.

“It’s very frustrating for me,” Conforto said after Sunday’s 4-3 loss to the Rockies. “It angers me. But it also motivates me to work on that and make sure those things don’t happen anymore.”

advertisement | advertise on newsday

Granderson off

Curtis Granderson’s .200 average and .287 on-base percentage aren’t cutting it for the Mets. But Collins acknowledged that he doesn’t have “a lot of options” for a replacement, meaning that Granderson will have to hit his way out of his funk.

Granderson was benched in Sunday’s series finale but is expected to play Tuesday against the Nationals.