Alonso, who currently leads the championship by 40 points from Mark Webber, has not been impressed with his Ferrari's speed over the last few races and claimed that it is anyone's guess where the title will go.
"We've seen in the first part of the season that two or three bad races can make you lose everything," Sky Sports News quotes Alonso as saying.
"In terms of performance, I think of the contenders, or the guys who are at the front, we are clearly the slowest.
"So we have a point advantage [but] we have a performance disadvantage. I don't think that we are favourite."
The Belgian Grand Prix takes place this weekend.