"I was cramping. I ran too much and I was just cramping," said Duba when speaking to the media.
The attacker has seen coach Nasreddine Nabi showing confidence in him in a season where he is enjoying more game time than in other campaigns.
"Yeah, we are getting used to him [Nabi]," he added.
"It's just that we have to adjust in every game according to the team we are playing against, but we are getting used to the way he wants us to play."