Barnsley opened the scoring through Max Watters but the Hornets hit back through Shamir Fenelon and James Hammond’s penalty.
But the Tykes restored parity before the break thanks to a Fabio Jalo wonder-strike.
Mael De Gevigney headed Barnsley in front just after the hour mark, but second half substitute Richards sensationally levelled with nine minutes to play to force an unlikely replay.
Here’s a selection of pictures from the game at Oakwell courtesy of Getty Images.
Mael De Gevigney headed Barnsley in front just after the hour mark, but second half substitute Richards sensationally levelled with nine minutes to play to force an unlikely replay.