"Ci tenau sy'n ennill y ras."

[btopps]

Is this an actual Welsh phrase or just a fun example for the course?

[ibisc]

Not an everyday expression! A proverb. But it does illustrate the particular pattern very well.

[AliT.Firef]

If it's not a proverb (or even if it is), surely 'It's a thin dog that's winning the race' should be accepted. (I am reporting back to my friend who knows the dogs better than I do, but can't see what's going on.)