TRENTON, N.J. — A golden retriever retrieved the No. 2 hitter’s bat, and then the Trenton Thunder’s special guest star stepped up to the plate in the first inning at Arm & Hammer Park.

A 40-year-old DH with 692 homers in the majors was in the minors, getting back in the swing.

Alex Rodriguez was supposed to come off the DL after recovering from his right hamstring strain and face Toronto Tuesday night in the Bronx. Instead, here was A-Rod in the Double-A Eastern League, facing the Blue Jays’ New Hampshire affiliate under the lights in a rehab game by the banks of the Delaware River, playing before 6,217 fans.

He finished 2-for-4 — popped to second; ripped an RBI single to center; bounced into a force; grounded a single into left — but didn’t run full speed during Trenton’s 11-inning, 3-2 win.

“First day back, good day,” Rodriguez said. “I saw the ball well and hit the ball pretty well. No setbacks. Everything felt good, strong.”

Since A-Rod hadn’t seen pitching in a game for three weeks, the Yankees rethought their plan Monday, figuring he shouldn’t return without a rehab assignment. So the new plan includes hitting again for Trenton Wednesday night. Rodriguez could return to the Yankees Friday at Tampa Bay, or possibly Thursday against Toronto.

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“As we talked about it as a group with (Brian Cashman) on the phone, I felt it was probably best that he just got a couple days of at-bats,” Joe Girardi said at Yankee Stadium. “. . . And then we can just take him on the road trip. . . . If he feels good after two days, I wouldn’t hesitate to call him here.”

“It’s more for knocking off the rust,” Girardi added.

A-Rod batted .194 in 20 games before injuring himself running to first May 3 in Baltimore. He hit .353 with three homers and six RBIs over the previous five.

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“There’s never a good time to get hurt,” Rodriguez said. “But that was unfortunate timing for me because I felt like it took me a little extra long to kind of get loose and get in the groove of my swing and kind of get in the cadence of the game.”

Carlos Beltran, meanwhile, has excelled as the primary DH.

“Any time Joe has options, that’s a great thing,” A-Rod said.

He also said he loved being around these minor-league kids. The feeling appeared mutual.

“The way he goes about his BP, he puts himself in different situations in games and he executes,” Thunder manager Bobby Mitchell said. “The guys were just like all eyes on him, even the other team. . . . It’s really impressive the way he goes about his business.”