The Welshmen came from behind to send Chasetown home with zero points.
Colwyn Bay 4 Chasetown 2
The Scholars started well but the first real chance came in the 40th minute when Muzzy Nduna forced a save from Andy Coughlin at his near post.
Colwyn took the lead two minutes later though. Craig Pritchard nipped through the visitors defence and fired home at the second attempt.
Chasetown went close to an equaliser in the final minute of the half with a Callum Cockerill-Mollett header narrowly over the crossbar.
Danny Cocks was a whisker away from an equaliser with a curling effort inches wide of the post.
The equaliser finally came when Will Whieldon’s corner was headed goalwards by Cockerill-Mollett and through the legs of Coughlin.
Whieldon turned provider again with a peach of a cross from the right and an even better diving header from Nduna.
Bay were awarded a spot kick with 70 minutes on the clock and Josh Brizzell made no mistake from the spot.
The topsy turvy nature continued and the Welshmen regained the lead with Lassana Mendes drawing keeper Curtis Pond and firing home.
Colwyn regained their composure and added a fourth goal as Ashley Woods slid home another for the hosts.