Last year, Alonso tried to add an Indy 500 win to his Monaco grand prix triumph, which would have only left Le Mans before him and the unofficial title.
But now, the McLaren driver’s forthcoming outing at Daytona is being regarded as a toe in the water of a potential Le Mans bid in 2018.
Former F1 driver Montoya said: “I think his chances are very, very good.
“He has a good chance to win because he is on a good team with a good car,” the Colombian told Spain’s Mara.
Montoya said Alonso came close to winning on debut at Indy last year.
“Really he lacked nothing,” he said. “Honda gave him a very good engine and he had a great car. Only mechanical failure stopped him, but that’s the thing with Indy — you have to have everything go right.”
Montoya therefore backed Alonso’s chances of joining Graham Hill as the only holder of the elusive ‘triple crown’.
“He certainly has the ability to achieve it, but it’s not easy,” he said.
“The truth is that I am closer than him,” Montoya, who has won both Monaco and the Indy 500, laughed.
“For me, I don’t know about Le Mans. We will have to see what happens with the Le Mans regulations and if there is any chance that Penske can do it in the future.
“I think it would be quite fun to try,” he said.
In that way, he said he and Alonso are quite similar as drivers.
“I think we are two drivers who are not afraid to try new things,” the former McLaren driver explained.
“I don’t see any other F1 drivers trying to do that. When you’re young and in formula one, you believe there is nothing beyond that.”
However, Montoya thinks Alonso’s chances of doing well in F1 this year are good, despite the awful McLaren-Honda project of 2015-2017.
“They should go much better with Renault,” he said, “even though it is true that things were finally starting to work with Honda.
“I follow it but for me formula one has never been the most exciting level of competition.
“American races are seen as a ‘show’ even more than a sport, but in Europe there are many traditionalist people who say it’s not like that. Let’s see how Liberty solves that,” said Montoya.