Cowdenbeath 2-0 Dundee
Second-bottom Cowdenbeath stunned Scottish Championship leaders Dundee, whose advantage over Hamilton was cut to one point.
Loan signing from Kilmarnock Rory McKeown marked his Cowden debut with a goal, drilling home before half-time.
Martin Boyle threatened an equaliser for the visitors but fired wide.
And Greg Stewart slotted home James Stevenson's pass to double the hosts' lead and secure the win that takes them to within three points of Raith Rovers.
The result is also a first defeat as Dundee manager for Paul Hartley.