I mean i agree, it was not actually given one of those boxes telling us that the match-up has started, so it's not officially the case.
However these are the fights that i always thought would happen, and seeing more and more interaction between King and Queen it makes them seem like a very fitting pair to mirror Zoro and Sanji on the opponent's side.
If i was forced to take a bet on this instance, my money would be on Zoro vs King and Sanji vs Queen. They fit best the roles of Mr1 and Mr2 or Kaku and Jabra in this arc, and power wise they are most fitting to push Zoro and Sanji to their limits and surpass them.