Creatures

without

flying

don't

untap

during

their

controllers'

untap

steps.

At

the

beginning

of

each

player's

upkeep,

that

player

may

choose

any

number

of

tapped

creatures

without

flying

they

control

and

pay

for

each

creature

chosen

this

way.

If

the

player

does,

untap

those

creatures.