Mali stunned Mexico 2-0 while Colombia, Portugal and Uruguay also took maximum points on the second day of the FIFA Under-20 World Cup in New Zealand on Sunday.

In a bizarre game in which two Mexicans were red-carded as was one from Mali, the outcome was determined by two goals in a three-minute flurry of action late in the game.

Mexico, the perennial CONCACAF under-20 champions, were a man up and firmly in control for most of the game but were unable to find the net.

Instead it was Mali who triumphed with two quick goals after they were reduced to 10 men and Mexico were down to nine.

Mexico should have scored shortly before half-time when Guillermo Martinez broke clear, but with the goal at his mercy he fired high and wide.

As passions rose, Mali's Hamidou Maiga was first to receive his marching orders for a second yellow card early in the second half.

With everything in their favour, Mexico then imploded as Diego Gama was sent off following an off-the-ball clash and Oscar Bernal was dismissed after earning a second yellow.

With a one-man advantage now in Mali's favour, they capitalised with Adama Traore heading home from a free kick in the 76th minute. Dieudonne Gbakle sealed the outcome three minutes later when he slammed the ball home.

Uruquay joined Mali as the other unbeaten side in Pool D when they beat Serbia 1-0 with a Gaston Pereiro goal.

It was a much tougher outing than Uruguay, the 2013 finalists, had expected and it was the Serbians who played the more positive football.

However, while they went close on several occasions they were unable to find the net. Uruguay made the most of their limited chances, with Pereiro's goal 12 minutes into the second half.

Colombia opened their campaign with a 1-0 win over Qatar, slotting in the Pool C game's solitary goal in the 24th minute.

Santos Borre laid the ball on for Joao Rodriguez, who fired home between the legs of Yousof Hassan.

The Chelsea forward, on loan to Portuguese club Vitoria, was unfortunate not to strike twice more in the first half as Colombia dominated possession.

In the second half, the initiative swung Qatar's way with Jassim Al Jalabi, Ahmed Alsadi and Sultan Alkuwari all applying pressure around the net -- although without fully testing Colombia keeper Alvaro Montero.

Portugal made a bright start towards downing Senegal 3-0 when Gelson Martins fired the fourth quickest goal in the tournament's history, netting after 26 seconds.

Senegal recovered from the early setback and there was little between the two sides until Andre Silva and Nuno Santos both found the back of the net in extra time.