Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
Roger Federer recovered from his shock defeat by Fernando Gonzalez with a 6-4 6-3 win over Russian Nikolay Davydenko in his second Masters Cup group match.
The world number one showed only flashes of his best but raised his game at the right times to take his win-loss record against Davydenko to 11-0.
Federer faces Andy Roddick in his final group match tomorrow.
Roddick became the first player to reach the semifinals when he crushed Gonzalez 6-1 6-4.
The Chilean never found the blistering form that accounted for Federer on Monday but Roddick was simply stunning.
The American spent a recent injury lay-off working on his general fitness and it showed.
His movement around the baseline and particularly at the net was far too much for Gonzalez who was broken three times.
Roddick, who had a match point against Federer at last year's Masters Cup, will go into his next meeting with the world number one brimming with confidence.
And Federer will surely have to step up a gear if he is to continue his winning run against Roddick, which stands at 10 matches.
He was unconvincing against Davydenko and his relief at coming through was evident in his roar of delight when the Russian sent a forehand long on Federer's first match point.
"It's a different situation coming back after losing," he said.
"I don't have the best record on making break points but I create many opportunities so eventually I will break through and break their will." - BBC