The Spaniard has won the Barcelona race just once - in 2006 with Renault - and has been hindered by uncompetitive cars in the three home races he has competed in with Ferrari.
This year, however, Alonso feels he has a car that will allow him to change the defensive approach of previous years.
But the Ferrari driver is aware that he will need a trouble-free weekend in order to be fighting for victory.
"Maybe it's the first time we arrive with a competitive car but that doesn't mean you will fight for top places if you don't do everything right and don't put together a good weekend," said Alonso.
"In the first four races we were competitive. We thought we could fight for the top places if the race was without problems. We will try here to have a clean race with no problems and if that will be enough to put us in contention for the victory it would be be nice.
"But if it's not possible then we will try and be as high as possible.
"It is a weekend we approach with a positive mentality and not a defensive mentality like the first three years at Ferrari."
The two-time champion is 30 points behind leader Sebastian Vettel after four races, having endured troubled races in Malaysia and Bahrain.
Alonso remains confident about his chances, however, thanks to the competitiveness of his Ferrari.
"Last year we were 1 or 1.5 seconds behind the top cars and we won by luck the race of Malaysia," he said. "This year we finished two races without problems and we finished second in Australia and won in China.
"It is a very different feeling and a different package we have this year, which brings us a good feeling that we can have a good championship.
"We are some points behind now, but the championship is long."
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