However, the game was far from over and Tondu scored 12 points, including two tries, to close the gap.
In truth, Tonmawr had just too much staying power and a stronger squad, but Tondu played some fine rugby and contributed greatly to an interesting match.
Both sides had good full backs - Tondu, in their experienced Dean Thomas and Tonmawr in Dino Roberts, the former Wattstown player, who was awarded man of the match.
Mark Roberts and Joe Heatley played splendidly in the Tondu backs and Nathan Brown was the pick of a hard-working pack, while Elliot Frewen was a swift wing for Tonmawr and replacement Andrew Gwynne had a huge second spell.
Dean Thomas landed a penalty for an early Tondu lead and wing Darren Thomas contributed to a wonderful length-of-the-field movement. However, Frewen's pace and a Luke Richards link sent wing Gareth John over and Richards converted to give Tonmawr a lead they never lost.
After 41 minutes Darren Ritchie sent lock Ben Davies clear for Richards to convert, though Tondu No 8 Ben Thomas almost scored after a thrilling touchline run.
Frewen snatched the third try from Gwynne's pass and Richards converted and then Ben Davies dribbled over in the corner for his second try.
Then, Tondu hit back as Brown's clever run set up Dean Thomas for a try that he also converted and, right on time, replacement wing Jonathan Humphries intercepted and ran in from 50 metres.