First-half goals from Jaze Kabia and Harvey Rodgers boosted Grimsby's League Two play-off bid with an assured 2-0 victory at 10-man Crawley.
The Red Devils had to make do with 10 men for almost the entire second half after captain Jay Williams received a straight red card, suffering their first defeat under new head coach Colin Kazim-Richards.
Kabia and Rodgers Strike Before the Break
Grimsby almost took the lead inside the first minute when the on-rushing Kabia put an angled shot wide, and defender Rodgers shot just wide for the Mariners before David Artell's side went ahead midway through the half when Kabia fired across goalkeeper Jacob Chapman after Andy Cook's assist.