PORT ST. LUCIE, Fla. — Lucas Duda might not resume baseball activities for at least two more days because of lingering soreness in his hips and back.

The first baseman originally was scheduled to start Saturday’s Grapefruit League home opener, an 8-6 loss to the Nationals. It would have been his first action of spring training.

On Friday, however, Duda had a cortisone injection in each hip that will require a few days to take effect. He did not work out with the team the previous three days.

Duda, 31, was limited to 47 games last season because of a stress fracture in his back. He hit .229 with seven homers, and his absence left the Mets without one of their most productive hitters. Duda hit 57 homers and knocked in 165 runs in the previous two seasons. He will be a free agent at season’s end.

Terry Collins doesn’t think Duda’s hip injury is related to the stress fracture. Nevertheless, the Mets will use other players at first base as a hedge.

Neil Walker already has taken grounders at first, and by next week, that group could include Jay Bruce and David Wright.

Said Collins: “We’ve just got to protect ourselves.’’

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Big step looming?

Zack Wheeler had his scheduled bullpen session pushed back a day to Sunday, a decision made by pitching coach Dan Warthen.

The new plan calls for the righthander to throw more pitches Sunday, which Warthen said could set him up to face batters for the first time since his Tommy John surgery in March 2015.

Wheeler’s throwing program had been slowed earlier in camp because of tenderness in his surgically repaired elbow. Warthen said Wheeler has encountered no physical issues since then.

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Banged up

Catcher Kevin Plawecki was helped off the field in the sixth inning after an awkward collision at the plate. The Mets announced that Plawecki suffered a bruised knee and was scheduled for precautionary X-rays.

“Fortunately, no damage,” Collins said. “Because it looked worse than it turned out.”

Plawecki caught a high throw to the plate, and just as he landed, the Nationals’ Rafael Bautista made a headfirst slide. Bautista’s shoulder slammed into Plawecki’s knee.

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Extra bases

Wright and Jose Reyes started in the same lineup for the first time since Sept. 28, 2011. Wright batted fourth and was the DH; Reyes led off and played third base . . . Michael Conforto collected an RBI single against the Nationals a day after homering in his Grapefruit League debut.