Kenilworth were 1-0 down at the break to a scrambled goal but can feel aggrieved to have been behind to their higher-level rivals after Adam Edwards, Matty Lendon and Harry Easterlow all went close.
The Midland Combination Division One side doubled their lead with a well-worked goal after the break, but the home side gained a lifeline within a minute when Easterlow scored his first senior goal with a cute finish into the top corner.
Kenilworth huffed and puffed to find an equaliser but had to wait until injury time to get back on level terms, Scott Easterlow matching his brother with a cool finish into the bottom corner.
Extra-time saw the hosts continue to press but it was Chelmsley who conjured up the winner, with their substitute pouncing after Ross Davis had saved the initial effort.
Manager Kev Kingham refused to be downbeat after the loss, saying the display augured well for the season.
“We showed character and pride and a lot of quality on the ball,” said Kingham. “If we continue to work hard it should be a good campaign.”
Goals from Becky Jones (2) and Tash Devis earned Town’s ladies a 3-3 draw against Crusaders.