Cregagh, who were playing at their home ground, looked in control for 39 of the 40 overs after the opening batsmen built a platform for a competitive total of 147 before the bowlers reduced Ballymena to 113-7.
However, stand-in skipper Glass, who was on 51, launched the ball over the ropes off every delivery to finish unbeaten on 87, much to the disbelief of the Cregagh players and the crowd at Gibson Park.
JOHN GLASS TAKE A BOW!He has just hit 36 off the final over and Ballymena are the 2021 Lagan Valley Steels 2021 c… https://t.co/ffhxM0XiPs
— Northern Cricket Union (@NCU_News) 1626379240000
He also walked away with the Man of the Match trophy while there was more cause for celebration in the Glass household after his older brother Sam had completed a hat-trick in the first innings to finish with three wickets for five runs.