Alonso has finished second in the last three races despite qualifying ninth, fifth and seventh for those events.
"I think this weekend we are not particularly strong," said Alonso.
"In the race pace yesterday we saw some problems, so I'm a little bit less optimistic in terms of winning the race or a podium finish for tomorrow. But we will try our best.
"At the start there is a very short space to Turn 1 so we will do all our attacks in Turn 3 and Turn 4.
"There's always some action in this race so we'll see what we can do, but we know that we'll also struggle tomorrow."
His team-mate Felipe Massa qualified one place behind Alonso, and reckons Ferrari's focus might have to be on those starting on its tail.
"I hope the car is a little bit better in the race compared to qualifying, but it definitely won't be an easy race," said Massa.
"We're not just fighting Red Bull and Mercedes. One of the Lotuses is in front of us and we have some other cars very close, like the Saubers.
"We're fighting with many other teams who are behind us but very close."