As the NBA prepares for the arrival of team guests into the bubble for the start of the conference semifinals this month, the league is requiring players to provide proof of "long-standing relationships" with non-family members, according to a memo obtained by ESPN.

The NBA and National Basketball Players Association negotiated terms that preclude players from hosting guests who would be deemed as wholly casual in nature, including "known by the player only through social media or an intermediary," according to the memo.

Those without "an established pre-existing, personal and known relationship" won't be allowed into the bubble, where each second-round playoff team has been allocated 17 hotel rooms for guests. The earliest guests could clear the quarantine process and join players is Aug. 31, according to the memo.

As one general manager told ESPN, the issue of casual acquaintances "could create problems within your team -- and maybe someone else's too" and has been a significant topic of discussion among organizations hoping to minimize internal drama as the playoffs unfold.