Speaking to reporters on Thursday at the Italian Formula One team's 'Wrooom' media event at the Dolomites ski resort of Madonna di Campiglio, the Spaniard singled out his former McLaren team mate as the strongest rival.
"Who is the strongest opponent, the strongest driver on the grid? Who is the one you have to keep an eye on? It is Hamilton - and it will still be Hamilton next year," he said.
"I am sure he will be able to win. He is a super good driver because he won every year with any car. He won in 2007 and 2008. In 2009 they started around two seconds off the pace with the McLaren and Hamilton was able to win races. And it was the same in 2010."
Alonso pointed out that Germany's Nico Rosberg won a race last year for Mercedes in a season when the car was largely uncompetitive.
On that basis, he said Hamilton "will be able to win more than one race."
Hamilton made his Formula One debut alongside Alonso at McLaren in 2007 and ended the season as overall runner-up, ahead of the double champion although tied on points, with four victories and podium finishes in his first nine races.
The Briton remains the only team mate to have beaten Alonso over the course of a season.
The 28-year-old, champion in 2008, has said he does not expect Mercedes to challenge for the championship this season and has also played down the chances of race wins before sweeping changes to the regulations in 2014.
Alonso said it was too early to say who his main championship rival would be - with that depending on a range of factors including the car, team, testing and luck - and he recognised Vettel's qualities at Red Bull.
Vettel, at 25 the youngest triple champion, beat Alonso to last year's title by three points after a final race in Brazil that could have gone either way.
"For sure in these three years there were moments when he was better than anybody else and he deserved these three championships," said the Ferrari driver.
Alonso also replied to a suggestion from Red Bull advisor Helmut Marko, in a recent interview, that he played political games while Vettel shut out all the chatter to focus on racing.
"I simply drive cars," he asserted, adding that Marko's comments appeared 'mixed up' and 'meaningless'.
"They say that they did not listen and they did not speak. They were saying they were not being influenced by what we said, but it means they did listen or someone woke up at night and read the comments - because they had to calm down," said Alonso.
The Spaniard was optimistic about the coming season, which starts in Australia on March 17, after Ferrari began last year with a car that was well off the pace.
"We can be faster or slower, but not 1.5 or two seconds off the pace. It is maybe impossible to be worse than last year, so I am confident," he said. (Reporting by Alan Baldwin, editing by Ed Osmond)