Widnes-based St Maries are one of the favourites for the North West Men's League Division Four title but the Gladiators pushed them far close than many had predicted.
Chester are much changed from the last season and handed debuts to wing Jef Bertenshaw and twins Lee and Mark Thomas, with all three making impressive starts.
With hooker Dan Rowett back in the fold, Mark Kingsley partnered Chris Pape in the halves and Paul Welch moved back into the back.
Despite missing a number of first team regulars through injury, Gladiators started the game in determined fashion and seemed to catch their hosts by surprise.
Dan Timperley - moved up to the front row - gave his best performance for the club while Olly Laxton demonstrated his massive improvement in the back row and Will Benson again impressing.
Welch put Gladiators into the lead with the game's first try and Kingsley looked to have landed the conversion, but the referee ruled his attempt unsuccessful despite both touch judges raising their flags.
Vikings hit back with an unconverted try to tie the scores before half time and the second half was hard fought with some brutal defence on both sides.
With the game heading to a draw, the hosts hit the front 10 minutes from time with a second unconverted try and held on for the win.
Fullback Simon Quinn was man of the match for Chester, who travel to Rochdale Cobras next.