It is mathematically possible that the first semi-finalists could emerge from this week's CAF Champions League action, but if form is anything to go by, the race for last four places is likely to extend past this fourth round of fixtures.

Group A leaders Al Hilal of Sudan and the top two sides in Group B, Heartland FC of Nigeria and TP Mazembe Englebert of Congo DR, could make sure of their berths with maximum points at the weekend. However, they would need to buck an obvious trend, as only one away win has been secured in the 12 Champions League matches played this year.

Al Hilal travel to Nigeria for a Sunday match-up with Kano Pillars, who trail thm in second place in Group A and will pull level at the top of the standings if they win. Pillars lost 2-0 to Al Hilal in Khartoum a fortnight ago but their Sudanese opponents are notoriously poor travellers and will be expected to struggle in the hostile confines of northern Nigeria. Should Al Hilal win, however, they would move to 10 points, enough to guarantee one of the top two spots in the section.

Beating Zesco is not impossible. We're a big team and we want to keep our chances alive.
Al Merreikh coach Mohamed 'Mazda' Abdallah

Zesco United revived their chances with an away win over Al Merreikh of Sudan earlier in August and now host the bottom-placed side in Lusaka in Sunday's other Group A match. The Zambians have seven key players out through a combination of injury and suspension.

Al Merreikh are not mathematically out of contention yet, but admit they face an uphill struggle. On their arrival in Zambia on Thursday, their coach Mohamed 'Mazda' Abdallah said: "Beating Zesco is not impossible. We're a big team and we want to keep our chances alive. We have to fight to remain in the competition."

In Group B, Heartland FC are away at Etoile Sahel, while Mazembe play Monomotapa in Harare. Both games will take place on Saturday. To date, all the matches in this section have been won by the home side but if there are away wins this weekend, the pair at the top will be six points ahead with two games to go, but crucially have the edge over their opponents on head-to-head results.

Etoile Sahel's 3-0 defeat at Heartland a fortnight ago was among the heaviest the Tunisian club have suffered to date in continental club competition. However, central defender Ammar Jmel is back from injury to strength the side for Saturday night's game at Sousse.

Mazembe claimed an emphatic 5-0 win over Monomotapa of Zimbabwe in Lubumbashi on 15 August but coach Diego Garzitto has warned his side against being over-confident for the reverse fixture. "We're playing for a win here but let's wait until [after] Saturday's game to talk about our chances of going to the semi-finals."

The fifth round of fixtures will be played on the weekend of 11-13 September, by which time the possible semi-finals permutations are likely to be considerably clearer.