A single incident from Liverpool's 1-0 home defeat to Arsenal on Sunday has reignited one of football's most contentious debates: should players go to ground to earn penalties, or should the rules protect those who stay honest?

The Isak incident that sparked the debate

In the second half at Anfield, Bradley Barcola delivered a cross into the Arsenal penalty area. Alexander Isak appeared to be in position to nod home an equaliser — but the ball drifted wide, and the Liverpool striker simply turned and walked back upfield to await the goal-kick.

Only on replay did it become clear that Jurrien Timber had a firm grip of Isak's shirt. Yet Isak offered no reaction, no protest, no appeal. Referee Andy Madley missed it. VAR official Stuart Attwell determined there was insufficient evidence to trigger a review.

Liverpool manager Andoni Iraola was blunt after the final whistle.