Reading's Ibrahima Sonko says he is "scared" ahead of the clash at Chelsea after receiving death threats after his collision with keeper Carlo Cudicini.
Cudicini was hurt in a collision with Sonko in October, the game that also saw Petr Cech suffer head injuries.
And Sonko is pensive ahead of the Boxing Day game at Stamford Bridge.
He said: "I've been scared. You have to take the letters seriously. Some people are nasty and capable of stupid things when it comes to revenge."
"This had nothing to do with Chelsea. It was stupid people with nothing to do other than sending letters"
Cudicini was carried off on a stretcher suffering from concussion, and Cech was left with a fractured skull after a clash with Reading's Stephen Hunt in Chelsea's 1-0 win.
Hunt received death threats, and Sonko has also been on the receiving end of hate mail.
He told The Sun: "That incident has gone away. But now the next game is coming up.
"Me and Stephen probably got letters from the same people."
The 25-year-old defender said: "At first it made me laugh, then when the second one came it started to get serious.
"I got scared. You don't know where the letters have come from so you don't know how to protect yourself.
"I was more worried about how and when they would do it. I can look after myself as long as I see it coming.
"But you don't know when it will happen and you have to start looking around you, being careful about who you are standing with."
Sonko added: "Knowing we are going to Chelsea next week, you think maybe this person will think about it again.
"This had nothing to do with Chelsea. It was stupid people with nothing to do other than sending letters."