The Tasmanian climbing star has experienced a subdued season, claiming his customary victory on Wilunga Hill at the Tour Down Under, but suffering a bout of bronchitis soon after that ruled him out of Paris-Nice.
His form has been behind his normal level since, but has shown promising signs at the Tour of California and the Criterium du Dauphine.
Porte will start the 2019 Tour not as one of the top favourites, which he has been in the past, but among a larger group of contenders without a standout.
Four-time winner Chris Froome's crash ruled him out of the Tour, and with defending champion Geraint Thomas crashing at the Tour de Suisse and displaying anemic form generally, the race is being viewed as a wide open affair.
"One thing I do agree with all the journos about is that it's a much more open race than previous years," Porte told The Examiner. "You never want to see what happened to Froomey happen to anybody and it really threw a spanner in the works for Ineos.
"He would have been the man to beat again. (Tom) Dumoulin the same as he was second last year and in the Giro. Without them the names are not quite as big."
21-year-old Egan Bernal (Team Ineos) enters the race as the favourite with the bookmakers after solid wins at the Tour de Suisse and Paris-Nice, while perennial Grand Tour contender Vincenzo Nibali (Bahrain-Merida) is coming off a hard fought second place finish at the Giro d'Italia.
"Nibali is coming from the Giro so you don't know how that will affect him," Porte said.
"G (Geraint Thomas) had a crash at Tour de Suisse but seems OK and in Bernal, Ineos have this wonder kid who seems to be able to do everything and being Colombian he will be good at altitude because they're all born at about 3000 metres.
"So it is wide open this year."
Porte's highest place finish at a Grand Tour is fifth in the 2016 Tour de France and the Tasmanian will be hoping that he can break his poor run of luck in the big race to better that finish.
