The siblings, of Paterson Drive, Law, earned Mua Thai third places in Birmingham to impress their club coach Stephen Mair, chief instructor at Team Glah-Hahn in Craigneuk.
"Both girls are excellent," Stephen (42) said.
"I was very impressed by how they performed in Birmingham and reckon they are both British champions of the future.
"Amy Leigh and Abbey Leigh are dedicated fighters who are never out of my gym.
"If they are in there any longer they'll be mistaken for a punchbag!
"In addition to their time in the gym, they do running and road work."
Carluke High pupil Amy Leigh, who fought in the 11 to 16 years 45kg category in Birmingham, and Law Primary youngster Abbey Leigh — who contested the nine to 11 years 22kg class — both did well against much more experienced fighters.
Mum Sandy Kerr said: "I couldn't be any prouder of the two of them.
"Stephen really encourages them to do well.
"After coming home and eating their dinner, they are desperate to go out to Thai boxing training.
"I'm glad the girls do the training, because there is nothing for them to do in Law. It keeps them fit, away from the street corners and out of bother."
For more information on this article, see this week's Carluke and Lanark Gazette, which is in the shops now.