The Mets and Chicago Cubs play a four-game series at Citi Field starting on June 14.

Here are five things to watch…

After leaving his start this past Friday against the San Diego Padres before the seventh inning due to right flexor tendinitis after throwing just 80 pitches, deGrom said his concern level was low. He has had no issues during his between-starts routine, and remains on track to get the start on Wednesday.

In four starts since returning from the IL after missing time due to a side injury, deGrom has thrown 63, 70, 85, and 80 pitches while not pitching beyond the seventh inning. And in the sixth inning against the Padres on Friday, while dealing with the flexor issue, his velocity was noticeably down.

How will he look against the Cubs and how many innings will he be allowed to pitch?

Peterson has had back-to-back nightmare starts, giving up four runs on eight hits in 2.2 innings against the Baltimore Orioles on June 8 after lasting just one third of an inning against the Arizona Diamondbacks (while allowing five runs) on June 2.

Whether Peterson’s issue is mechanical, mental, or something else, it’s fair to believe that if he is non-competitive against the Cubs on Monday that he’ll be removed from the rotation — at least temporarily.

The Mets’ options to replace Peterson aren’t ideal, but there’s only so many chances they can give him before going in another direction.

The Cubs have won five straight games, including a weekend sweep of the rival St. Louis Cardinals, and are tied with the Milwaukee Brewers atop the NL Central with a 38-27 record.

Joc Pederson has hit three homers in his last four games and Kris Bryant is having a resurgent season at the plate, but the Cubs have been carried mostly be their pitching during their winning streak, allowing just nine runs in five games.

Meanwhile, closer Craig Kimbrel has been nearly unhittable this season, so it would behoove the Mets to not be trailing late.

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Dominic Smith has gone 0-for-17 over his last four games, striking out five times and alternating between pounding the ball into the ground and hitting it softly in the air.

Before his recent cold spell, Smith was showing signs of coming out of what had been an early-season malaise, so hopefully the last four games are just a blip.

But if Smith’s struggles continue much longer, the Mets will likely have to slide him down in the lineup.

McKinney, who smacked two homers last Wednesday against the Orioles and two doubles against the Padres on Friday, has missed the last two games due to a knee issue.

The hope is that he’ll be able to return for the Cubs series, which would likely lead to Mason Williams being back on the bench.