Title holders Esperance became the first qualifiers for the 2012 CAF Champions League semi-finals by defeating fellow Tunisians Etoile Sahel 2-0 this weekend.
Karim Aouadhi put the 'Blood and Gold' ahead on 41 minutes in Mediterranean resort Sousse and Cameroon-born Yannick Ndjeng struck another goal midway through the second half.
Only Etoile supporters were allowed to watch the match at the Olympic Stadium because of security concerns and there was a pitch invasion after each goal which forced police to use teargas.
The result not only took Esperance to the last four in pursuit of the $1.5 million first prize and a 2012 FIFA Club World Cup place in Japan, it also endangered the chances of former champions Etoile joining them.
Etoile are contesting second place with Sunshine Stars of Nigeria, who won 2-1 at ASO Chlef of Algeria to open a three-ponit advantage and will qualify by winning at home against the Tunisians in the final round.
Esperance have 12 points from four victories and success in Sousse extended to 20 matches an unbeaten run in the premier Pan-African club competition extending back to the 2011 qualifiers.
Sunshine have seven points, Etoile four and the first appearance by Chlef in the group stage has quickly turned into a nightmare with no points after four consecutive losses.
In the probable event of Sunshine losing at Esperance on matchday 5 and Etoile defeating visiting Chlef, the clubs will go into the final round of mini-league fixtures with seven points each.
After losing at home to Esperance on matchday 1, Sunshine have drawn at Etoile and defeated Chlef home and away to bolster chances of a second consecutive semi-finals appearance in a CAF competition.
The club from south-western Nigeria reached the semi-finals of the second-tier CAF Confederation last year and put up a brave fight before bowing to Club Africain of Tunisia.
Sunshine, who travelled to Algeria without injured Osas Idehen and Okumu James, unavailable John Owoeri and Isaac Hele and suspended Ajani Ibrahim, triumphed via goals from Medrane Tamen and Akombo Ukeyima.
Tamen broke the deadlock on the stroke of half-time, fellow Cameroonian Anicet Eyanga levelled just after the break and Chlef had Sabri Gharbi red carded before Ukeyima struck the 72nd-minute winner with a scorching shot.
Etoile du Sahel's striker Jacob Meite (second left) vies for the ball with Esperance de Tunis' defender Walid Hichri (centre) and midfielder Wajdi Bouazzi (left) during their African Champions League football match at the Olympic Stadium in Sousse.