Larin, 30, scored the third goal in North Wales, restoring Southampton’s two-goal buffer before they ran rampant in the closing stages.
Larin’s physical presence frustrated home defenders, and the Canadian could have scored a hat-trick at the Racecourse Ground.
He sent a header onto the crossbar in the first half before Arthur Okonkwo pulled off a sharp save from his volley on the spin.
But Larin made no mistake with a one-on-one finish, having run half the length of the pitch, to cap off his evening with a goal.
“He was excellent. We didn’t really know who was going to step onto Finn Azaz. Cyle’s position changed a bit depending on their defenders,” Eckert explained.
“We knew we had him up against them in a couple of situations. He’s an excellent striker with his back to the goal, and he works a lot for the team.
“I’m very happy with his performance. We hit the crossbar very early on, twice. I think they all worked incredibly hard on the weekend, and the same today.
“We knew that once they get some time on the ball, they [Wrexham] have some rotations that you need to control and that are not so easy to pick up.
“It’s a lot of work for the ones that are furthest up the pitch, and I think they’ve done that very well.”