The Aprilia rider was cycling at Mugello on Thursday when he had a “big, big crash”, injuring his back, arm and “destroying” his heel.
He said he is now in “a lot of pain” and though nothing was broken in the crash, is unable to use his rear brake.
Despite his injuries, Espargaro finished ninth in the combined timings for FP1 and FP2, and will head straight into Q2 on Saturday.
Speaking about the crash, he said: “It was a stupid thing.
“I decided to go out to do two hours and it was quite foggy yesterday morning, so I said to myself okay, stay in the track, it’s more safe.
“Being on track, I was more relaxed so I was using my telephone like stupid and I had a big, big, big crash.
“I hurt all my back and arm and everything, big crash, but this is not the biggest problem.
“My heel is destroyed, I have a lot of pain, I have a lot of blood inside. We removed the blood for the second session, I had infiltration but not really working.
“I have a lot of pain and I cannot use the rear brake.
“I said sorry to the team many times so I will try my best as I did today to be careful in the last laps to put the bike into Turn 10, I will do the same for Sunday.”
Espargaro added: “I have a lot of pain. I race in my career with big injuries, I destroy both my hands and after one week of operation I race, no problem.
“I make many times the infiltration. After my left heel at Silverstone, I raced on Sunday, it was not a disaster.
“But this time it’s nothing broken but it’s full of blood, it’s something on the ligament or something we will discover on Monday, but for sure there is something that is not the bone that doesn’t allow me to use the rear brake.
“When I use the rear brake it’s crazy the pain, it’s unbelievable. I did the foot on the foot deck and used just the front brake and this obviously limits our performance, but I made it to put the bike in Turn 10.”
Espargaro said the team had considered adding a thumb brake to his RS-GP ahead of Friday’s sessions, but believed it could cause more problems and possibly a crash.
He also said that his FP2 result was “not that bad”, which led the team to decide to keep things as they are.
Asked whether he had taken painkillers to manage the pain, he said: “I used big painkillers, we tried to put the infiltration, but when we tried to put the infiltration on the foot, the blood was pushing the solution out and we removed a lot of blood from the heel.
“So really, nothing works there, so it’s more about ice and removing the blood, because every time I use it, it will make more blood to protect the sole.
“When there is more blood, when I put the boot and I move, I see stars – it’s crazy the pain.
“The only thing we can do is remove the blood and ice, ice, ice.”
