Argentina 1, Nigeria 0

Johannesburg — Even though Lionel Messi baffled Nigeria’s defenders, Argentina still had to sweat out Diego Maradona’s first World Cup victory as a coach.

Gabriel Heinze scored on a diving header in the sixth minute, the only one of seven shots on goal Argentina converted in its win Saturday.

Heinze took advantage of weak defense to power in his header from 12 yards off Juan Sebastian Veron’s corner kick. After that, it was nothing but missed chances for Albiceleste.

“The team made good moves, but we ended up suffering. That’s the law of soccer,” Maradona said. “Thank God we won the game.

“To begin a World Cup in winning fashion gives you a certain sense of calmness. The only thing that concerns me is that we won a big game.”

The Nigerians struggled for much of the match to contain Messi, and striker Gonzalo Higuain also failed to convert three good chances.

Critics say he rarely plays well for his country, but Messi posed a threat to the Nigerians all day.

South Korea 2, Greece 0

Port Elizabeth, South Africa — South Korea opened the World Cup like it wanted to repeat its 2002 run to the semifinals. Greece looked like it was stuck in 1994.

Lee Jung-soo and Park Ji-sung each scored and South Korea beat lackluster Greece in Saturday’s first Group B match.

“If we had been a little bit calmer, we could have had an even better result,” South Korea coach Huh Jung-moo said. “In terms of scoring goals, it could have been a little bit better for us.”

Playing in its seventh consecutive World Cup — including its 2002 appearance in the semifinals, when it co-hosted the tournament with Japan — South Korea controlled the tempo from its first scoring chance on.

Greece has only been to the tournament once before, in 1994.

Back then, the Greeks let Argentina score just two minutes into the opening game. The Greeks improved this time around — by five minutes.

Ki Sung-yong curled in a free kick from near the left corner flag in the seventh minute.