PORTO SEGURO, Brazil (AP) — Germany repeated their feat from four years ago by opening the World Cup with a 4-0 victory. Now they are hoping there won’t be a repeat of their second game in South Africa when they take on Ghana today.

The Germans routed Australia to start their 2010 campaign, but then lost to Serbia 1-0 in the next game. After beating Portugal 4-0 in Brazil on Monday, Germany are wary of another letdown in Fortaleza against Ghana — the same team they beat 1-0 in their third game in South Africa to reach the knockout round.

“The second match from four years ago is a warning,” Germany defender Per Mertesacker said. “We opened very well, then lost. We’ll have to take it very seriously.”

Ghana lost their opening match 2-1 to the United States and can’t afford another defeat, while Germany would all but clinch a spot in the knockout rounds with another win.

A big downside from the opening win, though, was an injury picked up by central defender Mats Hummels. Hummels did not practise with the team on Thursday and a decision on his fitness won’t be made until shortly before the match.

“I hope he will be able to play, we’ve just started getting accustomed to playing alongside each other and to have more confidence,” Mertesacker said. “It would be a little question mark if Mats can’t play but we all know what we have to do.”

The rematch also brings together again the Boateng half-brothers, Jerome, a Germany defender, and Kevin-Prince, a forward for Ghana, who started on the bench against the United States. Regardless of whether he starts today, the Germans are quite familiar with their opponents.

“Ghana are a very physical team, they try to outplay you, they want to shine,” Mertesacker said. “They are a dangerous team and we’ll have to be very clever, especially in the heat. We’ll have to play good defence.”

Ghana team officials have denied reports of a “player revolt” against coach Kwesi Appiah following the loss to the United States.

Ghana’s Joy FM said players — in particular Kevin-Prince Boateng, who plays for Schalke in Germany — were unhappy with Appiah’s tactics in the defeat to the Americans. AC Milan’s Michael Essien also started on the bench.

The radio station misinterpreted the reason why a news conference at the team base in Maceio was postponed on Tuesday, the Ghana Football Association said, denying players had refused to report for the conference.

“We wish to state emphatically that the report is absolutely false and has no basis in fact,” the GFA said. “There is no player revolt against the coach of Black Stars and no player or players have been involved in any mutiny in the wake of the 2-1 defeat to the United States.”

Essien was back in training after picking up a toe injury in the World Cup loss to the United States. The Ghana team said Essien missed training Wednesday but returned to practice Thursday.

Ghana made the quarter-finals at the World Cup in South Africa four years ago, only the third African team to go that far.

African teams are under the spotlight at the World Cup after simmering discontent in the Cameroon and Nigeria camps. Cameroon’s players initially refused to board a plane to Brazil over what they felt were poor bonuses and Nigeria’s preparations have also been distracted by issues surrounding player payments.

Only one of the five African teams at the World Cup, Ivory Coast, won in the first round of games. Nigeria drew 0-0 with Iran and Cameroon, Ghana and Algeria all lost. Cameroon lost their second, 4-0 to Croatia, and are already out of the tournament.

Germany are likely to stick to the same formation without a true striker, which worked so well against Portugal when Thomas Mueller scored a hat-trick. Captain Philipp Lahm will continue in defensive midfield, assistant coach Hansi Flick said.