Reference article
Brown Tufted Duck
Brown Tufted Duck is a local rival who offers a race in Grassland.
Challenge
Speak to this duck in 
Grassland to enter 
Brown Tufted Duck’s Race. The entry requirement is Running level 10.
Dialogue
If you can beat me I'll give you an invite to the tournament I don't waste time with newbies. I won't race anyone with a running level below 10
Race guide
See Brown Tufted Duck’s Race for the course and rewards.