The 23-year-old championship leader's hat-trick of wins knocked soccer off the front pages in Spain on Monday, with sports daily Marca dedicating its first 13 pages to his San Marino Grand Prix triumph.
"After three victories I am now feeling very strong in the championship but these victories are also going to generate an excess of euphoria so we have to be cautious," said Alonso, looking forward to the Spanish Grand Prix in Barcelona on May 8.
"It is going to get harder to win from now on as Ferrari is becoming more competitive and (Kimi) Raikkonen was pushing on dangerously today in the McLaren before he had to retire."
"The truth is that day-by-day my chances of winning the next race in Barcelona are getting less and less."
The Renault driver started second on the grid at Imola on Sunday and was only able to take the lead when Raikkonen came to a halt on lap nine.
Alonso was then forced to play a masterful strategic game to hold off seven-times world champion Michael Schumacher's Ferrari over the last dozen laps and deliver his team a fourth win in four races this season.
"I had hoped to get a podium finish but I never thought I would get my third consecutive win, so the team is enormously happy," said Alonso.
"This is the kind of win that I like where you spring a surprise, especially in difficult circumstances."
"I was convinced that Schumacher wouldn't get past me as long as I didn't make a mistake, and managed to slow him down," continued Alonso.
"I was surprised at first that he was so far back. I thought that was that, and that I wouldn't have to worry about him, but he got past a lot of traffic at his first stop to close on me.
"I think I have had tougher duels than today's though, for example last year with (Jenson) Button in Hockenheim."
Alonso leads the championship standings with 36 points, double the total of his nearest rival, Italy's Toyota driver Jarno Trulli. German Schumacher has 10 points.
