In the second round of their welterweight bout at the O2 Arena, Santos was dropped by Page with a flying knee to the head.
"I'm under observation now and will have surgery in the United States," Santos told MMA Fighting. "I had a serious injury, but Bellator is giving me all the support I need."
His ex-wife, MMA fighter Cris "Cyborg" Justino, took to Instagram to ask for thoughts and prayers.
Fight fans Please say a prayer for my Ex husband Cyborg Santos. Many of you watched him fight on Spike TV this weekend when he suffered this injury while fighting in London. Cyborg is still in the hospital in the UK, and they are not sure when he will be able to fly again. He has not had surgery yet and their is worry the brain can continue to swell causing more damage. Click The link In My bio to donate to his #GoFundMe and support him and his family at this time. Thank you God for your protecion, The dr said this very Easily could have been life threatening. Please show your support for the fighters and share! 🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷 🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷🇧🇷Fãns de luta façam uma prece para o meu ex marido Cyborg Santos ,muitos de vocês assistiram ontem a luta dele na Spike TV,onde ele sofreu este ferimento enquanto lutava em Londres ,ele ainda está no hospital e não tem certeza quando ele vai poder voar de volta pra casa, @bellatormma é responsável por todo procedimentos médicos que ele precisar para resolver este problema porém ele não vai poder trabalhar por um tempo e nós vamos arrecadar ajuda pra ele através do #gofundme para os fãs patrocinarem ele e sua família nesta hora difícil, Obrigada Deus por sua proteção!! O medico disse que ele poderia estar em risco de vida,mostrem seu apoio aos lutadores e compartilhem isto!!! No meu Perfil do Instagram esta esta o link ajudar! #GodToGlory #figtherlife #teamcyborg #evangelistacyborgsantos #bellator158 #London Spanish 👇
Santos, 38, detailed the injury to MMA Fighting as a serious fracture in his forehead.
Despite the injury, he said he plans to continue his MMA career.
"I'll be back soon," he told MMA Fighting.
Page took to Twitter on Sunday to wish Santos a speedy recovery.
I would like to express my best wishes to @CYBORG121 & his family, as he is currently being held in hospital for a fractured skull— Michael Venom Page (@Michaelpage247) July 17, 2016
Page had made headlines Saturday when he celebrated the victory by putting on a Pokemon cap and rolling a Pokeball at Santos in an ode to "Pokemon Go," the popular mobile app.