Hernandez, whose only other goal this season came in the Football League Trophy – also against Chesterfield – haunted the Spireites again at Vale Park.

Lee Bonis’ header was the visitors’ first effort on goal but Vale keeper Marko Marosi helped it over the bar. Marosi produced another tip-over from Ryan Stirk’s long-range shot.

Vale entered the game as the division’s joint-lowest scorers and produced virtually nothing in attack throughout the first half. But they led at the break, thanks to Hernandez’s 45th-minute strike. The Cuban’s neat chip over his marker should have been dealt with but he capitalised on hesitant defending to poke home.

Precious little was created by either side in the second half. Hernandez sent a weak effort straight at Ryan Boot and Chesterfield’s Louie Marsh and Josh Koroma gave Marosi equally routine stops to make.

Boot kept Chesterfield in contention by saving from Keyrol Figueroa, but the visitors couldn’t find a late equaliser and fell to their fourth league defeat.