Speaking after surviving a match point to beat Czech Jan Hernych 6-7, 7-5, 6-0 in the first round of the Estoril Open, the Argentine world number five said: "Everyone is thinking the same, that he looks unbeatable and is playing great.
"He is one of the favourites for the French Open."
The 18-year-old Nadal has won four claycourt tournaments already this year, including back-to-back titles in Monte Carlo and Barcelona this month and reached a career-high ranking of seventh this week.
"At the moment he is playing with lots of confidence and taking advantage of that but as soon as his confidence starts to go and he starts playing worse, then of course we will be able to find weaknesses."
For Nadal in 2005, read Guillermo Coria in 2004. Gaudio's countryman looked similarly unbeatable a year ago as he swept all before him on the European clay courts, until Gaudio himself upset the odds in a five-set thriller in the French Open final.
"I hope it will happen the same way this year and I can beat Nadal in the final in Paris -- that would be nice," added Gaudio, the second seed in Estoril.
Hernych, ranked 71 places below Gaudio, coped better with the blustery conditions in a topsy turvy opening two sets and served for the match at 5-4 in the second.
But after losing his match point his game collapsed and thereafter he won only a handful of points.
Gaudio said he had turned in a Jekyll and Hyde performance.
"There were two Gastons out there today, a bad one and a good one. I wasn't moving well but I had some luck on the match point and then started playing better.
"I saw that he was having problems closing out the match and was feeling nervous so when he missed badly on an important point, that gave me the confidence to turn it around."
Gaudio's main rivals for Estoril begin their challenges on Tuesday as the triple Spanish threat of former Roland Garros champions Juan-Carlos Ferrero, Carlos Moya and Albert Costa take to the courts. Reigning champion Juan Ignacio Chela of Argentina will also be in action.
Earlier on Monday former world number four Jelena Dokic crashed out of the WTA tour event 6-2, 3-6, 6-2 at the hands of Ukraine's Alyona Bondarenko.
Sixth seed Dally Randriantefy of Madagascar made short work of Portuguese qualifier Neuza Silva, winning 6-2, 6-2.
