Meaning: I can beat you even with disadvantages. Use examples.
Rewrite 1: I could whip you even with my arm in a sling.
Rewrite 2: I could whip you while hopping on one leg.
Rewrite 3: I could whip you with both arms tied behind my back.
Rewrite 4: you couldn’t beat me if I had my back turned toward to you.

Comment: This is something most often recited by children, so you can afford to be extravagant with your claims, even a bit adventurous.

More reading about clichés
What I found when I googled “clichés”:
• In Cliches in Action Scenes, “Author Network offers a number of helpful articles on the business of writing - Clichés in Action Scenes by Linda Adams.”