Rosberg and team-mate Lewis Hamilton took a commanding one-two in first practice, when shod on the new medium compound, but both were outgunned by Sebastian Vettel once the field switched to softs in practice two.
Both men also suffered with graining while attempting long runs on the soft rubber.
"It was a good day in general, but the soft tyres didn't last very long, that's for sure," Rosberg said.
"Sunday will tell us if we have been advantaged or disadvantaged.
"It's interesting because the tyres are different and we have to adapt - some set-up changes and things like that.
"It's also an opportunity for us, if we can understand them quicker than others, to take another step compared to everybody else."
Rosberg thinks the competitive order could still shuffle over the weekend, adding: "It looks like still on one lap we are quite quick and also on the longer run a similar situation, but it might still shuffle things around a little bit.
"A few tenths here or there and you might see a different grid and different race results."
Hamilton said set-up issues, rather than tyre complaints, had been to blame for his slide from first to eighth over the two sessions.
"It was alright, nothing special, and then we made some changes and we've gone backwards a little bit," he explained.
"We'll backtrack a little bit, make some other changes and we'll be fine tomorrow, I'm sure.
"It was feeling like it was going pretty well at the start of P1, P2 we had a little bit of an imbalance in the car but it's fixable."