The Ducati Marlboro rider lost the lead of the championship with an under-par performance in Jerez, where he could only finish 11th after running off the track twice.
And although admitting that Estoril is not one of his preferred tracks, he sees no reason why he cannot be back in the hunt for victory.
"This circuit is not one of my favourites," said the Australian. "Everyone has the same opinion here: it is a difficult track, very technical, and it is not really enjoyable.
"But we've always had good results here and always been quite fast here, so with the Ducati Bridgestone package we should be fast enough to be pushing for another win. It will be difficult, though, as there are a lot of people going quick this year."
Stoner said that Jerez had been one of the worst weekends of his MotoGP career.
"It was very frustrating," he explained. "All weekend we put in a lot of effort to make the bike go around that circuit and I thought at worst we could have got fifth. And with the lap times after we went off track, I think we showed we could do it.
"But no matter how much effort I put in, nothing went right. I saw a position that was reasonable, and I knew I could have got into the top seven and I think been in the battle for fifth.
"Then, when it slipped away from someone else making a mistake on me I thought, 'okay I made a mistake at the beginning of the race and it can't get any worse than that.' And it happened again. I couldn't believe it. It was a very disappointing weekend, very, very disappointing."
autosport.com