2d beat em up throw system

Hi!
I´m having an issue with my beat em up.
I created a grappling system, it works fine, but I´m having an issue.
the player can grab/throw two enemies at the same time!
To perform a grapple you have to be very close to the enemy, but for gameplay porpousses I can´t use
box colliders for the enemies or the player, just one (small) circle collider for the ground detecting, so, you can be really close to two enemies at once, the are just separated by the ground detecting collider, they don´t use the same x space, but they can be pretty close.
I was thinking of an algorithym that may detect the distance of every enemy at grappling distance, and then select the one wich is closest to the player, an perform the grapple/throw on him, but I´m afraid it may be to slow…
What do you think, guys?
(sorry but I´m an European Spanish, so my english might suck).

Checking once on a throw event for which enemy is closest won’t be too slow, go for it.