Pinto's lunge left the referee with little choice but to brandish the red card.
However, the incident was made all the worse for the 30-year-old player's protests. At one point he almost head butted Sanchez before being led away by one of his team mates.
Others joined in the protests, with Fernando Couto actually holding Sanchez around the face and FIFA's video panel will no doubt want to watch the replays of this ugly confrontation.
It is remarkable the shaken referee didn't give Couto his marching orders as well.
The only member of the Poruguese bench who didn't protest was coach Antonio Oliveira, who looked on bemused. He knew it was a bad tackle and Pinto deserved to go.
It was evidence of Portugal's frustrations after failing to take control of a match they needed to win.
The pressure on the Koreans to reach the second round was huge even though they only won their first game at the World Cup finals against Poland last week. Having tasted success, the country's football fans were desperate not to have to swallow failure.
That co-hosts and fierce rivals Japan beat Tunisia earlier in the day to guarantee their place as group winners didn't help either.
The home team did have the ball in the net in the 31st minute but Sanchez ruled out Seol Ki Hyeon's tap in after a foul on goalkeeper Vitor Baia by defender Choi Jin Cheul.
Just after the break Seol was unlucky with a header which just went wide of the post.
But clear-cut chances were few and far between before Park's goal completely opened up the group.
The Koreans will now play Italy in Daejeon in the last 16 on Tuesday while the USA, despite their defeat to Poland, will play Mexico the day before in Jeonju.
