These sides played three divisions apart last season, and there was a clear gulf in class on the field during the opening 45 minutes this afternoon.
Matt Sparrow, playing his first senior Scunthorpe game since 2010, fired United ahead on the half-hour mark.
Winnall doubled the lead six minutes before half time, latching onto a fantastic pass from Terry Hawkridge before finishing clinically.
The second half was a low-key affair, but it exploded back into life right at the death.
Scunthorpe's otherwise perfect day was blemished in stoppage time, as Eddie Nolan was sent off for picking up a second yellow card in the act of conceding a penalty.
However, United's clean sheet remained intact as Louis Briscoe blasted the subsequent spot kick high and wide.