PORT ELIZABETH, South Africa — Ghana believes a physical and defensive Niger will pose its biggest challenge yet when the teams clash in a decisive Africa Cup of Nations Group B tie Monday. Second favorite behind Ivory Coast to win the tournament, the Black Stars of Ghana top Group B with four points after an opening-day stumble against the Democratic Republic of Congo when they drew after squandering a two-goal lead. “We have watched Niger play DR Congo and Mali. They are a very physical and tactically disciplined team and this match will be more difficult than our first two,” warned midfielder Derek Boateng. “Niger are no pushovers and we have to do more to beat them,” added Bristol City midfielder Albert Adomah. “No game is easy here, but we are getting better as a team and, hopefully, we will move to the next stage.” Ghana coach Kwesi Appiah said his team will have to be very fit and prepared for a physical battle at Nelson Mandela Bay Stadium in this Indian Ocean city. Espanyol midfielder Mubarak Wakaso misses the game as he is serving a one-match ban after picking up his second booking of the tournament for his goal celebration against Mali. Wakaso is also nursing a knee complaint, but coach Appiah disclosed he should be fit for the quarterfinals, assuming the Black Stars qualify.Ghana's only injury worry is Italy-based striker Richmond Boakye-Yiadom, who has not fully recovered from a groin injury sustained during a training camp in Abu Dhabi. The Black Stars will be up against the pumped-up Mena (Gazelles) of Niger, who defied the form book to hold DR Congo 0-0 for their first point in the competition after a defeat by Mali last week and losses to Gabon, Tunisia and Morocco in the 2012 Cup of Nations. Niger skipper Moussa Maazou has admitted it will not be an easy game against one of the top teams in the tournament. Issiakou Koudize is the only concern for Niger as he has a knee injury and German coach Gernot Rohr said the 22-year-old defensive midfielder will face a late fitness test. In the other encounter, meanwhile, flamboyant Frenchman Claude Le Roy puts a proud Africa Cup of Nations coaching record on the line Monday when his Democratic Republic of Congo outfit tackle Mali in a must-win Group B game. The bespectacled 64-year-old with a mop of fair hair has been to six previous tournaments from 1986 with Cameroon and Senegal (twice each), Ghana and DR Congo and never failed to reach the knockout stages. Le Roy steered Cameroon to the 1988 title two years after the Indomitable Lions finished runners-up under his guidance, and he took Senegal to fourth place in 1990 and the quarterfinals of the following tournament. DR Congo were next to benefit from the vast knowledge of the nomadic Le Roy, making the last eight in 2006, and the man who is never shy to speak out on African football issues, guided 2008 host Ghana to a bronze medal. But the unpredictable Congolese Leopards must bring the Malian Eagles down to earth and collect maximum points at the 60,000-seat Moses Mabhida Stadium in the Indian Ocean city of Durban to reach the knockout phase. The countries have met twice before in the Cup of Nations with Mali edging the then-Zaire in a thrilling seven-goal 1972 semifinal and the central Africans turning the tables with a 1-0 win 22 years later. — Agencies