Watford midfielder Will Hughes is adamant he was caught inside the penalty area.
Hughes was brought down by Andy Robertson, but the referee waved play on.
Liverpool scored a few minutes later, much to the disappointment of the home crowd. And they eventually ran away with a 3-0 win.
Speaking about the penalty decision, Hughes said to theWatford Observer after the game: "I've not seen it back again, but I felt a little contact and I've gone over.
"Whether or not it's enough contact (to give a penalty) I'm not sure. We'll have to wait and see with the replays."