Mariners boss Neil Woods warned his players they cannot consider a bid for promotion back into the Football League unless they improve drastically from Tuesday's 2-0 friendly loss at Stirling Albion.
Woods conceded the scoreline flattered his side's performance, and the result was particularly disappointing as it came so soon after Saturday's impressive display against Sheffield Wednesday.
"You cannot get away with only playing well in one game, you have to do it week-in week-out," he told the Grimsby Telegraph.
"We are not good enough to coast and go through the motions. No disrespect to Stirling Albion, they are part-timers and congratulations to them for the effort they put in, but you had one side that fought harder and worked harder.
"They could have been four of five goals up in the first 10 minutes. We were never in control and only made fleeting chances. Some of the decisions players made with the ball were flabbergasting."
Grimsby are spending the week training at Stirling Albion as they continue their preparations for the new season.
Peter Bore suffered a hamsstring injury during the match and was substituted as a precaution, he and Lewis Gobern (thigh) will be rested for Saturday's game at Winterton Rangers.


