Luanda - No calculators are needed to work out the task facing Ghana in Tuesday's final Group B game - a win and nothing else is required against Burkina Faso if the four-time champions are to make it through to the Africa Cup of Nations quarter-finals.
The Black Stars are sweating on the results of a scan to the injured knee of Michael Essien, a player of such influence that his absence could make or break their Cup campaign.
Essien, who only played a bit part in his country's opening 3-1 loss to Ivory Coast, hobbled out of a training session on Sunday and was taken to hospital for tests.
Ghana's media officer Randy Abbey told AFP: "Michael suffered a right knee injury in the training session this morning.
"He was taken to a local hospital for a scan and we'll get the results back tomorrow and then have a clearer idea of whether he can play."
Essien's absence would be a colossal blow to Ghana who face Burkina Faso at the 50 000-seat November 11 Stadium in the Angolan capital.
Ghana are one point behind Burkina Faso who put themselves in a sound position to qualify when coming away from their opening game against Ivory Coast with a goalless draw and a precious point.
Essien arrived in Angola late for the tournament because snow delayed his flight from London and has been struggling to recover from a hamstring injury sustained playing for Chelsea in the Champions League last month.
He was kept on the bench until half-time against Ivory Coast last Friday in Cabinda by Serb coach Milovan Rajevac to avoid aggravating the injury and his second-half presence on the pitch could not prevent a heavy defeat.
Ghana arrived in Angola with a raft of key players missing forcing Rajevac to field a largely inexperienced side.
Of the Burkina Faso test he said: "Our next match is a question of double or quits."
Rajevac suggested the lopsided scoreline against the Ivory Coast did not do his side justice.
"We didn't play as badly as the score suggests. Most of the time we played well but unfortunately we didn't get the breaks."
After Essien's training setback it looks as though lady luck has yet to smile on the first team from Africa to qualify for the 2010 World Cup.
Burkina Faso set out a defensive stall against the Ivory Coast and the ploy worked a treat as European-based stars like Didier Drogba and Kolo Toure were held at bay.
Burkian Faso coach Paulo Duarte said: "That goalless drew has allowed us to start thinking of qualifying for the last eight. Now we have to take on another World Cup qualifer in Ghana, but my team has the ability to put up a good performance."
Togo, the other country drawn in Group B, withdrew before the tournament kicked off last Sunday after the bus convoy carrying them into Angola was attacked in the restive northern Angolan enclave of Cabinda.