By Mark Gleeson In Cape Town

Six former winners dominate this year's African Champions League and make it, arguably, the most fiercely contested since the round-robin format was introduced to the competition six years ago.

Each of the two groups has three former holders, setting up a potentially bruising battle for the top two places in each group.

The round-robin stage determines the semi-finalists, who face each other in November.

Defending champions Al Ahly of Egypt are the top seeds in group A, with Raja Casablanca of Morocco and TP Mazembe of DR Congo as serious contenders.

Ahly ended a 14-year drought to win the trophy last year and have made several key signings as they prepare for the new season.

Raja play TP Mazembe in Lubumbashi

Jo Bonfrere comes in as coach and Yasser Radwan and Mohamed Omara have returned after long spells in the German Bundesliga.

Ahly start the defence of their title at home to dark horses Jeanne d'Arc of Senegal, whose summer sale of Abdoulaye Diagne Faye has made their chances of getting to the last four very remote.

Raja, the other fancied side in group A, get an early test of their credentials in Lubumbashi on Saturday when they play TP Mazembe, whose last Champions League crown came over 30 years ago.

Group of death

Group B looks the hardest on paper.

Esperance of Tunisia, Asec Abidjan from Cote d'Ivoire and Zamalek, the other Egyptian representative, have equal chances of getting a semi-final place.

Asec have a tough opener against Zamalek

Zamalek got their Champions League campaign underway in Cairo with a cracking 3-1 win over Asec on Friday night.

Mozambique's Costa do Sol, who face Esperance on Sunday in Maputo, are expected to be the whipping boys of this group.

Esperance have been training in South Africa over the last two weeks, in order to replicate the conditions they will come up against when they face the Mozambicans.

But they have do without Skander Souayeh, banned by FIFA for six months after failing a doping test on the eve of the World Cup.