Bangladesh's match with Afghanistan will be more challenging. Sri Lanka was a weak team against Bangladesh. Meanwhile, Afghanistan is a better team than Sri Lanka, so it will be more difficult for Bangladesh to face Afghanistan.
Both Sri Lanka and Bangladesh are stronger than Afghanistan. The betting odds is slightly in favour of Bangladesh against Afghanistan. But the players of Bangladesh plays with the fear in most of the matches. This is the reason for their defeat in several matches. Anyway, I think Sri Lanka will win against Afghanistan. So, whoever wins between Afghanistan and Bangladesh will qualify for the super four.
In order for Bangladesh to qualify for the semi-finals of the Asia Cup, several equations have to come in Bangladesh's favor at the moment. First of all Sri Lanka won against Bangladesh by a big margin so Sri Lanka is tension free for now and Sri Lanka will definitely try to play the match against Afghanistan free. Bangladesh must win by a big margin against Afghanistan to qualify for the semi-finals because if Bangladesh can't win against Afghanistan by a big margin and if Afghanistan can beat Sri Lanka in their last match then Bangladesh's dream of qualifying for the semi-finals will end so Bangladesh must win against Afghanistan. Besides, the dream of going to the next round can be fulfilled only if the victory has to be secured by a big margin.