Nottingham Forest manager Nuno Espirito Santo says Danilo suffered a broken ankle in the opening-day draw with Bournemouth.
Danilo sustained the sickening injury after just six minutes at the City Ground after landing awkwardly following an aerial challenge with Antoine Semenyo.
The Brazilian received nine minutes of treatment, with club staff using blankets to shield him from the crowd, and left the field on a stretcher with his left leg in a splint.
He went to Queen’s Medical Centre where a fracture was confirmed by staff.
Nuno said: “It was a horrible moment for everybody, he is at the hospital now, we have just got the report of the doctor, still some exams, but he has broken his ankle.
“It is serious, we are going to miss him not only on the pitch, he is a wonderful boy. You know him, always smiling, always with this joy and wish him the best.
“I think he is leaving hospital just now and he is going to be assessed tomorrow and after tomorrow.
“It is serious but the good news is he is stable, he is speaking, he is aware so just needs time.
“I have no idea on the timeframe, I just wish it is short because he is a very important player for us.”
Forest looked like rallying to the three points in support of their stricken team-mate after going ahead in the 23rd minute through Chris Wood.
They missed chances to put the game to bed in the second half and were punished when Semenyo converted from close range in the 86th minute.
Cherries boss Andoni Iraola said: “Probably you feel a little bit of relief because at the end we recovered a point, we came here with the idea of winning game with the three points.
“We didn’t want to start by losing, it is a difficult team to play against when you are behind.
“But I think we kept pushing, it is at least fair we got one point and at the end of the game we finished stronger and were closer to winning it.”
On Danilo’s injury, the Spaniard added: “The most important thing is his injury, we could see straight away, I was watching it and I suppose everyone realised it is going to be a very bad injury.
“I hope it is not going to be as bad as it looks. But it looked a really bad one. The game has had a lot of interruptions, we didn’t have fluidity.”
