The 17-year-old, who moved to Anfield from Celtic last summer, was at the centre of an angry row involving several players as chaos took over.

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Liverpool’s youngsters secured their passage to the next stage of the competition on Wednesday courtesy of a penalty shoot-out.

However, the scenes of celebration soon turned to chaos as players from both sides became embroiled in a melee.

Winger Doak actually missed the first kick for the Reds but they still managed to prevail 6-5 after sudden death following a 1-1 draw.

The trouble erupted after Porto’s decisive miss.

Liverpool youngsters raced to goalkeeper Harvey Davies to celebrate their triumph.

But within seconds a huge scuffle broke out at the edge of the box.

Cameras missed what started the trouble, but Doak and several of his team-mates were seen sprinting towards the incident which was out of shot.

Then a number of punches appeared to be thrown as players and coaches tried to diffuse the situation.

Doak was spotted being dragged away by his fellow Liverpool players.

And as the cameras zoomed in on the drama, the Scotland U21 international was spotted with blood coming from a cut on his lip.

The angry scenes resulted in three red cards being dished out.

Two Porto players were sent-off while Liverpool’s Lewis Koumas was also dismissed after the whistle.

Doak, who had been booked during the game itself, did manage to avoid any further punishment after the drama.

Liverpool are now able to look forward to the quarter-finals.

But they will take on another Portuguese side, Sporting Lisbon, in the last-eight.