The sides clash again in the final this weekend in St Helens and a depleted Gladiators outfit had to dig deep to secure the win, keeping them top of the Division Four table.
Chester got off to an excellent start at The Cheshire County Sports Club with Joe Hickey and Paul Welch crossing for tries and Aled Davies converting both for a 12-0 advantage.
The Stags mounted a response and two quick-fire tries brought them to within two points, but the home team answered back with Welch touching down for his second and skipper Mark Kingsley going the length of the field to make the score 24-10 at half-time.
Garswood struck first in the second period to close to within eight but Craig Jones burst clear for Gladiators to stretch the lead once more and then prop Kellum Friday crashed through to put the hosts 32-20 ahead.
In an end-to-end contest, the Stags came back again and scored twice to get within eight points, but fit-again Daniel Munt marked his return to the team with a brace of tries to put the result to bed.
Billy Brickhill crossed late on to seal the points for Gladiators before the visitors went over for the final score of the afternoon.
Chester's attentions now switches to the NWML Shield final, which takes place at the home of Thatto Heath Crusaders. Gladiators reached the final with wins over Westhoughton Lions, Rylands Sharks A and Orrell St James A.