Dover Athletic suffered their first defeat in four games as Grimsby Town maintained their promotion charge with a 1-0 win at Crabble.
The Mariners top-scorer Lenell John-Lewis scored the only goal of the game, his 15th of the season, in the sixth minute.
It was the visitors sixth win in seven games and sees them third on the table, just three points behind leaders Barnet while Dover remain 10th.
But the result might have been different had Dover not had a penalty appeal waved away after defender Sean Francis' header appeared to be handled on the line in the final minutes.
John-Lewis' goal arrived after Dover goalkeeper Mitch Walker had saved his initial shot before the rebound fell kindly for the striker to put away to the delight of the travelling Grimsby fans.
Boss Chris Kinnear's side responded with Stefan Payne and Nicky Deverdics both having efforts easily saved by Grimsby goalkeeper James McKeown.
Dover then needed Walker to be at his best to deny Grimsby doubling their advantage five minutes before half-time. And he was.
Walker produced a fantastic save to somehow keep Aristote Nsiala's close-range header out after he looked destined to score.
Dover pressed for an equaliser after the break and opportunities came and went for Payne, Chris Kinnear Jnr and substitute Dan Holman.
Walker then saved well from Nathan Arnold before another Dover sub, James Poole, saw his effort go narrowly wide.
Dover piled on the pressure in the final minutes but it went unrewarded with Francis' header cleared off the line, McKeown saving from Poole before Francis just failed to get a touch on the ball from Ricky Modeste's shot in the final seconds.
Dover: Walker, Essam, Francis, Orlu, Raggett, Sterling, Kinnear Jnr (Cogan 85mins), Deverdics, Modeste, Murphy (Holman 58mins), Payne (Poole 83mins). Subs not used: Wynter, Taiwo.