counterchallenge
glove
defy
dare
rechallenge
appeal
test
provocate
challengeful
superchallenge
heckle
throw down the gauntlet
challengee
challengeable
hurdlesome
overchallenge
challenge
rub along
run for one's money
challenging
extract
rise
obstacle-ridden
come hell or high water
no matter what happens
foreset
stumblingblock
whatever may come
double dare
manage
multichallenge
go hard or go home
sweep aside
rough sledding
hoop
hard time
trickily
enodation
mountain to climb
clutch
copout
push water uphill
triumph
counterdifficulty
problem
rigour
trouble
killer
trickiness
take the bull by the horns