Chesterfield ended Oldham's 100% start to the season at home with a 2-1 win at Boundary Park.
Paul Cook's men led at the break thanks to Lee Bonis but Favour Fawunmi opened his Oldham account to equalise five minutes into the second half.
But within two minutes, Chesterfield restored their lead through Dilan Markanday's close-range finish.
Latics had comfortably beaten Port Vale and Swindon in their previous home games, but they were on the back foot in the 18th minute after Louie Marsh's shot hit the hand of Gus Scott-Morriss and the referee pointed to the spot.
Mat Hudson denied Bonis from 12 yards, but the striker reacted quickly to turn in the rebound to make it 1-0.
Fawunmi got on the end of Jamie Robson's left-wing cross and equalised with a free header in the 50th minute.
But the Spireites were back in front inside two minutes with Markanday securing a first win in four games from close range.
Match report supplied by PA Media.
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