Edward Chilufya gave Zambia the lead in the 51st minute, tapping the ball home after Portugal goalkeeper Diogo Costa had saved Enock Mwepu’s shot, and the win was sealed when Fashion Sakala fired in at the near post with a quarter of an hour remaining.

Helder struck in stoppage time following Mangani Banda’s save, but it proved to be in vain for Portugal who were guilty of missing a series of chances.

Diogo Goncalves, Andre Ribeiro and Xadas all had their fair share of opportunities in the second-half, but they wasted them.

Joining Zambia at the top of the Group C standings are Iran, who beat Costa Rica 1-0 at the same venue later in the day.

Mohammad Mehdi Mehdikhani secured the victory in the 81st minute, when having found himself unmarked he chested the ball down and drilled low into the bottom left corner.

Iran’s victory was their first win at the tournament since the inaugural edition, held in Tunisia in 1977.

The country is competing at the event for only the third time.

There was also action in Group D today as Japan came from behind to claim a 2-1 victory over South Africa at the Suwon World Cup Stadium.

Grant Margeman opened the scoring for South Africa in the seventh minute, when he chested down a lofted through ball in the box before finishing past goalkeeper Ryosuke Kojima.

Japan, who last qualified for the tournament in 2007, came out firing in the second-half and were level within three minutes of the restart as Koki Ogawa converted a cross from the left.

South Africa goalkeeper Mondli Mpoto got his hands to the ball, but only after it had crossed the line.

Ritsu Doan completed Japan’s comeback in the 72nd minute, curling a shot beyond Mpoto's reach into the far corner after some impressive link-up play with substitute Takefusa Kubo.

Today's later match in Group D saw substitute Rodrigo Amaral score a superb free-kick in the 76th minute to help Uruguay beat Italy 1-0.

Amaral smashed the ball from the corner of the penalty area into the top corner to save the blushes of captain Nicolás De La Cruz, who had a penalty saved by Andrea Zaccagno just before half-time.

The penalty was awarded after official Walter Lopez consulted the Video Assistant Referee (VAR) to assess a challenge on Joaquin Ardaiz when the Uruguayan was attempting a close-range shot in the area.

Action in South Korea is scheduled to continue tomorrow when Groups E and F get underway.

Group E sees France face Honduras and Vietnam go up against New Zealand at the Cheonan Sports Complex.

Ecuador's clash with the United States and Saudi Arabia's meeting with Senegal make up the Group F line-up at the Incheon Stadium.