Mohamed Salah said the death of Liverpool teammate Diogo Jota in a car crash had left him "frightened" to return to the club as the Premier League champions postponed the return of some players for pre-season training.
The Portugal forward and his younger brother Andre Silva, died in the early hours of Thursday after their car veered off a motorway in Spain and burst into flames.
Mourners gathered at a wake in Portugal on Friday ahead of the brothers' funeral on Saturday.
Jota's Liverpool teammates have spoken of their struggle to comprehend his death, with captain Virgil van Dijk writing on Instagram that he was "absolutely devastated and in total disbelief".
Liverpool manager Arne Slot said everyone associated with the club owed it to Jota to "stand together and be there for one another".
Egypt international Salah paid tribute to Jota on Friday.
"I am truly lost for words," last season's Premier League top-scorer posted on Instagram. "Until yesterday, I never thought there would be something that would frighten me of going back to Liverpool after the break.
"Teammates come and go but not like this. It's going to be extremely difficult to accept that Diogo won’t be there when we go back.
"My thoughts are with his wife, his children, and of course his parents who suddenly lost their children. Those close to Diogo and his brother Andre need all the support they can get. They will never be forgotten."
Jota had married his partner Rute Cardoso on June 22, posting a video of their wedding on Instagram just hours before the accident. They had three children.
The first group of Slot's Liverpool squad were scheduled to be at the club's training complex on Friday for the opening round of physical tests after their post-season break.
But their return has reportedly been pushed back until Monday.
Liverpool's first pre-season match is against Preston on July 13.
The club have opened a book of condolence and lowered flags to half-mast.
Fans have left flowers, scarves and shirts at a makeshift shrine outside Anfield and there are similar scenes at Wolves' Molineux Stadium, where Jota played previously.