Alexander Isak's transfer from Newcastle to Liverpool sparked strong emotions among Newcastle supporters.
Now he faces his former team at St James' Park for the first time.
Because in the opening round of the Premier League, Newcastle are hosting Liverpool, and when Isak arrived at the stadium, the home fans chanted "rat, rat, rat".
There were also loud boos every time the Swedish striker had the ball during the warm-up.
The match is in progress.
