(CNN) -- Argentina's star-studded line-up began their World Cup campaign with a 1-0 victory over Nigeria in their Group B opener in Johannesburg on Saturday. A goal from defender Gabriel Heinze after six minutes was all that separated the two teams after an inspired display from Nigeria goalkeeper Vincent Enyeama. But South Korea ended the day on top of the group following a 2-0 victory over Greece in Port Elizabeth earlier on Saturday. Goals from Lee Jung-Soo and Park Ji-Sung gave the 2002 semifinalists a comfortable win over the 2008 European cvhampions. Argentina 1-0 Nigeria Enyeama could do little to stop Heinze's powerful early header from a Juan Sebastian Veron corner, but he kept his team alive with a string of acrobatic saves to deny World Player of the Year Lionel Messi. Diego Maradona was delighted to secure his first victory as a World Cup coach, but critical of his strikers for failing to make the game safe. "When you don't kill things off in front of goal you can pay a heavy price. They almost got a draw -- we missed loads of chances," Maradona told AFP. "Players such as Leo Messi and Higuain knocked in around 60 goals last season between them, yet today it was almost as if they couldn't set their sights on goal. "But the win means we can be calm -- we are in the right track." 
Who were the 2008 European champions?
Germany