After the break there were two good chances for Tunisia centre forward Taha Yasine Khennissi as he broke free of the centre backs and got on to the end of balls through the middle.
The two teams also missed a penalty each in the second half of the encounter.
- Algeria will play their seventh AFCON semi-final, their first since 2010, having qualified only twice in their previous six.
"It was a big fight until the last minute, it was a wonderful match, I think my players wanted it to go to extra-time thinking Algeria were more exhausted", Rohr said post-match, as per Reuters.
According to the Algeria coach Djamel Belmadi, the right winger hasn't allowed that club success to go to his head.More news: Roy reunited with Kumar Dharmasena who will umpire World Cup final
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"We played too deep, we didn't put enough pressure on the opponents", he said.
Regarding the match itself, Belmadi said his team should have scored more than one goal in the first half but lost their way a little before fighting back. It helps Mahrez that he is at the heart of a team whose parts are all functoning smoothly.
Arguably the game was the best so far played in this tournament. "But this crop of players wants to write their own history", said Belmadi. "The result was logical", Madagascar coach Nicolas Dupuis said. Now 28, Mahrez might easily be a world champion by now.
When asked if that behavior was acceptable and whether he had spoken to the player about it, the Algeria manager replied: "I am not really sure that this is the place to talk about this".
"The semifinal is an equal stage for the four teams remaining in the competition". After the win over Guinea in the last round he was clear about the route ahead. "We deserved to score the goal and I think we could've scored more but then in the second half I think we had a hard moment for 15 minutes where we were under pressure", said Belmadi.