Brittney Griner will remain in custody in Russia for at least another month ... a judge just denied her request for house arrest, forcing her to stay in jail for another 30 days.
The 31-year-old WNBA superstar appeared in a Russian courtroom on Friday morning with the hopes of getting out of jail ... but her attorney told the Associated Press that did not happen.
The attorney, Alexander Boikov, did say, though, that because of the short nature of the custody extension .