Alonso currently has a 40-point advantage at the top of the standings, having won the Malaysian, European and German Grands Prix.
But his strong season has come as a surprise given Ferrari's very tough start to the year, and Alonso remains pessimistic about his car's pace.
"I think nothing has changed over the summer," the Spaniard replied when asked whether he felt like the title favourite.
"When you stop for four or five weeks, and you see the point you need to talk about F1 for some days and you see the classification, it looks like a big advantage for us. But if there are two or three bad races it changes everything.
"And in terms of performance, out of the contenders or the guys at the front, we are clearly the slowest.
"We have the points advantage but we have a performance disadvantage so I don't think we are the favourite."
Alonso highlighted Ferrari's lack of pace during the totally dry Hungarian GP weekend, which followed stronger performances in the rain-affected British and German events.
"The difference from pole position in the last race was eight tenths of a second, which is a little bit too much," he said.
"We need to improve that situation. We will see how much it is here and at Monza because they are two strange circuits in terms of characteristics of the car - you need low downforce compared to other circuits, so anything can happen in these next two grands prix and hopefully we can score some good points.
"Then the next point of reference is Singapore, at that point we must close this gap to pole position."