Liverpool fans chanted the name of Diaz, who joined for an initial £37.5 million in January 2022, as their team maintained their 100% home winning run in the league.
The 26-year-old had been due to play before news emerged on the eve of the match about his parents.
“It’s a worrying situation for all of us,” said Reds boss Klopp before the game. “It was a pretty tough night. I’ve never had that before. It’s a new experience I never needed.”
The late change did not disrupt the Reds on the pitch, however, with Klopp’s team having now gone a year without losing at home in the league.
Liverpool finished a distant 22 points behind champions Manchester City last season, but with more than a quarter of this season gone, they are proving much more of a threat at the top of the table.
But for Forest keeper Turner, they would have won by a more handsome margin as the Americans made fine saves to deny summer signings Ryan Gravenberch and Szoboszlai.
But Turner was then involved in the error that led to Salah making it 3-0 in the 77th minute.
He was well outside his area when Szoboszlai launched the ball forward from his own half, with the in-form Salah taking advantage of the mix-up between the keeper and Toffolo to score his 10th Liverpool goal in all competitions this season.
The Egypt forward joined Harry Chambers (1922) and John Aldridge (1987) in achieving the feat of scoring in each of the opening five home league matches of a season.
