CHICAGO — Michael Conforto’s transition to centerfield continued on Tuesday, when for the second day, he took fly balls at what will be his new position. But he won’t see actual game action there for a few days.

“We’re going to ease him in,” said manager Terry Collins, who instead started Curtis Granderson in centerfield.

The original plan had been to play Yoenis Cespedes in center just for Tuesday night’s game. But after he still had difficulty running at full speed with his tender right quad, Collins scrapped that plan and kept him in left.

Collins also hadn’t planned on using the 35-year-old Granderson in center, a position he has largely given up since signing with the Mets. But for Collins, experience was the priority.

“You play outfield, you see the ball and catch it, that’s really it,” said Granderson, who downplayed the position change, before misreading the first fly ball he saw on Monday night.

Meanwhile, Conforto played rightfield, where he made four starts during his three-week stint at Triple-A Las Vegas. He even earned an outfield assist, throwing out Jake Arrieta trying to score.

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But rightfield appears to be a temporary stopover. “We just wanted to get a few days of getting balls off the bat out there,” Collins said. “And one, I didn’t think, was sufficient.”

Duda moves forward

As expected, first baseman Lucas Duda began baseball activities for the first time since landing on the disabled list on May 23 with a stress fracture in his back.

Duda was hitting just .231 with seven homers in 39 games, though a season ago he hit 27 home runs while helping to anchor the middle of the Mets lineup.

Extra bases

Mets videos

Granderson, a Chicago native, held a baseball camp on Tuesday for about 150 kids that included a college tour at the University of Illinois-Chicago . . . The Mets and Cubs will wear throwback uniforms in Wednesday afternoon’s series finale ahead of this weekend’s Hall of Fame inductions. Six other teams are also wearing vintage uniforms.