Part-time competitor Sebastien Loeb is the only man who has beaten Volkswagen star Ogier so far this season.
Having won three of the four rounds to date, Ogier already holds a 54-point championship advantage over nearest rival Mikko Hirvonen.
Ostberg led Ogier on the opening morning of the last round in Portugal, only to crash out while ahead.
The M-Sport driver denied that his mistake came because he was having to go beyond his limits to challenge Ogier.
"He is beatable," Ostberg insisted.
"What happened in Portugal was not because of pushing too hard, there was some confusion with the pace note.
"I believe my pace is getting quicker and quicker and, trust me, I am not scared of Ogier."
Ostberg is currently fourth in the standings, 70 points behind Ogier. Third in Sweden is the Norwegian's only 2013 podium so far.