Rapid Reaction: Mets 6, Reds 3

NEW YORK -- A day after Lucas Duda had the heroics with a pair of two-run homers, the guy who lost the first-base competition had the big moment.

Ike Davis had a pinch-hit grand slam against J.J. Hoover in the bottom of the ninth to lift the Mets to a 6-3 win against the Cincinnati Reds on Saturday afternoon at Citi Field.

The only thing missing was Justin Turner to deliver a whipped-cream pie during the postgame celebration. Jonathon Niese did the honors instead.

It was Davis’ third career walk-off homer.

The last walk-off grand slam for the Mets: Jordany Valdespin on April 24, 2013, against the Dodgers’ Josh Wall.

The Mets also successfully challenged an umpire’s call for the first time this season during the pivotal frame.

Juan Lagares opened the bottom of the ninth with a walk. Anthony Recker then attempted to sacrifice Lagares to second with the Mets trailing, 3-2.

First baseman Joey Votto pounced on the bunt and tried to get the lead runner. Second-base ump James Hoye ruled Lagares out, but Terry Collins challenged the call and successfully had it overturned after a two-minute, 14-second review.

Ruben Tejada, attempting to sacrifice both runners ahead, then walked to load the bases with none out.

That prompted Collins to turn to Davis to pinch hit.

Hoover was handling the closing duties with Aroldis Chapman and Jonathan Broxton on the disabled list.

How did the Mets get in the predicament?

Dillon Gee, cruising through a stellar outing in the eighth, surrendered a two-run homer to Brandon Phillips on pitch No. 100 as Cincinnati took a 3-2 lead.

Southpaw Scott Rice had been waiting to enter to face the next two batters -- the lefties Votto and Jay Bruce -- with a runner on third and the Mets leading by a run. So Phillips likely was Gee’s final batter regardless of the outcome of the one-out faceoff.

Gee also allowed a fifth-inning solo homer to Ryan Ludwick. Gee’s line: 7.1 IP, 6 H, 3 R, 3 ER, 1 BB, 4 K, 2 HR.

Curtis Granderson had lifted the Mets to a 2-1 lead in the sixth with his first homer with the ballclub. The two-run shot against Johnny Cueto landed in the upper deck in right field.

Cueto had held the Mets hitless until Tejada's one-out double in the fifth.

It’s a hit: Leadoff hitter Eric Young Jr. had a seventh-inning infield single, snapping his hitless drought at 15 at-bats to open the season. He earlier reached base on an error by second baseman Phillips.

Duda day: A day after belting a pair of two-run homers, Duda went 0-for-4 with three strikeouts.

Entering the series, Collins indicated Davis likely would start once against the Reds in order to keep his bat sharp for pinch-hitting. So Davis figures to find himself in the lineup Sunday.

K zone: The Mets collectively struck out 10 times, upping their season total to 53. That is the franchise record through five games, topping 44 in 1968, according to the Elias Sports Bureau.

What’s next: Niese will be activated from the disabled list to pitch the homestand finale. He opposes right-hander Alfredo Simon at 1:10 p.m. Sunday.

Wilmer Flores is expected to be sent to Triple-A Las Vegas to clear the roster spot for Niese’s addition. The Mets had been carrying an extra bench player and four starting pitchers.

Flores joined the Mets when Daniel Murphy went on paternity leave and remained because Chris Young landed on the disabled list with a right quadriceps injury. Flores should play more shortstop than second base in the near future with the 51s.