Mendez-Laing and Joe Bunney put Dale 2-0 ahead at the break with calmly taken finishes, both assisted by Ian Henderson.
The home side pulled one back early in the second half through Paul Ennis, but Mendez-Laing bagged his second to seal the win in the final 20 minutes.
Assistant Manager Chris Beech took charge of this Dale side, with Keith Hill at the day’s other friendly against Stockport County.
Jonny Diba started in goal, with a back four of River Humphries, Kevin Gibbons, Brian Barry-Murphy and Scott Tanser. Matty Lund, Callum Camps and Donal McDermott made up the three in the middle, with Joe Bunney, Ian Henderson and Nathaniel Mendez-Laing part of a front three.
There was an injury blow for Dale inside the first ten minutes, when a late tackle on Lund saw him hobble off to be replaced by second year scholar Matthew Gillam.
It didn’t upset Dale’s rhythm though, as they took the lead just two minutes later. A fine through ball from Henderson found Mendez-Laing, who drove into the area and placed a calm finish beyond Hakan Burton.
Former Dale man Matthew Flynn was at right back for Curzon Ashton, and he tried his luck with a half volley from 25 yards which flew over the crossbar.
Henderson then headed a Tanser cross over the bar, before the skipper turned provider again for Dale’s second. Another perfectly weighted through ball inside the full back found Bunney, who finished under the goalkeeper with his right foot to double the lead.
The home side were restricted to efforts from range, with Ryan Brooke and Ryan Watson firing off target, before Paul Ennis saw his shot comfortably saved by Diba.
Henderson will feel he should have done better just after the half hour mark, when he sliced wide after a pull back from Gillam.
It was roles reversed minutes later when Henderson’s chip found the youngster, but Gillam scuffed his effort wide from just inside the area.
Diba had to be alert three minutes before the break when he dived to his left to keep out a header from Niall Cummins at close range.
Beech’s side had pressed well from the front for the first 45 minutes and that nearly led to a third goal on the stroke of half-time. Henderson closed down the Curzon Ashton goalkeeper and momentarily stole the ball from him outside the area, before Burton made a sliding tackle to win the ball back.
There was just one change at the break with Josh Lillis replacing Diba, and he was thrust straight into the action. He flew to his right to save a header from Joe Guest, before the Curzon Ashton man turned the ball back into the box where it was bundled home by Ennis.
Ennis could have equalised a minute later when one-on-one with Lillis, but the Dale stopper made a good save with his legs. Curzon substitute Daniel Cockerline did have the ball in the back of the net again, but he was ruled offside from Guest’s left wing cross.
Cockerline had a golden chance to level the scores midway through the second half with a free header in the middle of the goal, but he headed over to the relief of the Dale defence.
With just under 20 minutes remaining, Mendez-Laing doubled his tally and restored Dale’s two goal cushion. He latched onto a great ball and rounded the goalkeeper, before keeping a cool head to finish with defenders around him.
With the game winding down Gibbons was replaced by first year scholar Isaac Ward at centre half.
Early first half substitute Gillam did well to engineer some room inside the area before seeing his left foot effort turned round the post by substitute goalkeeper Cameron Mason. The corner came to nothing, and
Dale made it two wins a day to go with the 1-0 win away at Stockport County.