Sainz left McLaren at the end of last year to join Ferrari, but Norris had continued his impressive form, scoring two podiums so far this season.
McLaren rewarded Norris for his impressive form by handing him a new multi-year contract, announcing last week that he would remain with the team until at least the end of 2023.
Speaking about Norris's new deal, Sainz was confident his former teammate had the ability to lead McLaren to the very top in F1 over the coming years, naming him as one of the best drivers on the grid.
"I think there are a bunch of drivers now that are on a very similar level of performance," Sainz said.
"I would include Lando among them, that they are potential world champions, and they just need the right car to win it.
"I would include myself, I would include Charles [Leclerc] of course, and many others. The level in Formula 1 is so high that unfortunately, we are more dependent on what the team is capable of rather than I think what we can do.
"But I believe Lando has the potential to win and take McLaren to the top."
Sainz and Norris both finished on the podium at last Sunday's Monaco Grand Prix, finishing second and third behind race winner Max Verstappen.
With an average age of 23 years, 11 months and 28 days, it marked the third-youngest podium in F1 history, only trailing the 2019 Brazilian Grand Prix and the 2008 Italian Grand Prix.
Sainz felt the results showed that F1 is "in good hands for the future", noting the tiny margins between the front-runners on the grid.
"The level of drivers this year in general is super high," Sainz said.
"When you see the qualifying laps, when you check the qualifying laps of everyone and you see not only the young drivers but also people like Lewis [Hamilton] etc, it's just an incredible level.
"I'm glad to be sharing this grid with so many talented people and comparing myself against them, and see how you can do.
"It pushes you like no other, and it's good as a racing driver to feel pushed and to feel like you need to always keep finding new limits."