SAN FRANCISCO — Mets righthander Rafael Montero will take the mound in Sunday’s series finale with his latest chance to show that he’s capable of being a big-league starter.

Montero, 26, earned his opportunity with two strong appearances out of the bullpen. After being recalled from Triple-A Las Vegas on June 14, Montero has allowed one run in 6 2⁄3 innings in two relief outings.

“I’m very encouraged,” Terry Collins said.

But Montero often has had trouble taking that success to the mound as a starter, when he has paid the price for his tendency to nibble around the strike zone. In two starts this year, he’s 0-1 with a 10.80 ERA.

“Confidence is everything here, and his last two relief outings, he’s thrown very, very well,” Collins said. “So I hope he just takes what he’s done and takes it into [Sunday].’’

Montero’s start will mark the Mets’ last in a six-man rotation. After Monday’s scheduled day off, the Mets will return to a standard five-man configuration.

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Outfield shuffle

Michael Conforto, one of the Mets’ top offensive producers, was out of the starting lineup against the Giants. One day after his first three-hit game since May 23, he pinch hit for Jacob deGrom in the ninth and hit an RBI single.

Instead, Collins started Curtis Granderson, who entered play 4-for-15 with three homers against Johnny Cueto. But in his first three plate appearances, Granderson struck out twice and grounded back to the mound. He tripled off Sam Dyson in the eighth and later scored.

Leftfielder Yoenis Cespedes (1-for-5) also started Saturday night, talking his way into the lineup even though Collins had considered giving him a day off. It was Cespedes’ fifth straight start.

The Mets have tried to be careful with Cespedes since his return from the disabled list with hamstring and quadriceps issues.