Forest Green Rovers and Wrexham battled to their first goalless draw since Wrexham dropped down into the Blue Square Bet Premier in 2008.
Chris Maxwell, having returned to Wrexham on loan in the January transfer window, made a fantastic save to keep out Reece Styche's first-half shot.
But Danny Wright's header almost won it for the Dragons after the break.
Both sides stay in the play-off places but the draw allowed Grimsby to increase their lead at the top.
VIEWS FROM THE DRESSING ROOM
Forest Green Rovers manager Dave Hockaday told BBC Radio Gloucestershire:
"I just felt in the first half we were playing the occasion more than the game. In the second half, I thought we got going and looked a lot more purposeful and more dangerous.
"I thought their dominance originated from ours and gave them a chance to put the ball in the box from free-kicks.
"I thought their keeper kept the ball out brilliantly at times. I really proud that we've gone toe-to-toe with Wrexham and stood our ground
"I really enjoyed that game, I thought it was a tight top game and want my players to experience more of that."
Wrexham player-manager Andy Morrell told BBC Radio Wales:
"Would I have taken a point before? I probably would have but I thought we played really well. Defensively I thought we were magnificent, defended probably and how we should do. It's nice to have a clean sheet for once.
"But it's a shame we couldn't nick one at the other end, which I thought we did. If we would have played like this on Tuesday, we would have won."