His movie, with its highly emotional story centred on an indigenous maid working for a middle-class family in Mexico City in 1971
Mexican director Alfonso Cuaron won the Golden Lion top prize at the Venice film festival on Saturday for "Roma", which critics called not merely a movie but "a vision".
With its highly emotional story centred on an indigenous maid working for a middle-class family in Mexico City in 1971, it has been hailed as Cuaron's most personal film - and also his best.
Cuaron told reporters that in an incredible coincidence "today is the birthday of Libo, the woman the movie is based on. What a present!"
The film industry bible Variety said "Roma" is likely to go down as a "masterpiece".
"It is no mere movie - it's a vision... where every image and every emotion is perfectly set in place," said critic Owen Gleiberman.
Cuaron "dunks us, moment by moment, image by luminously composed image, into a panorama of the hurly-burly of Mexico City."
The Italian press declared it "sublime" while for The Guardian's Peter Bradshaw it was a "complete triumph.”
Venice has become the launchpad for the Oscars race, with Hollywood heavyweights jostling for attention in a line-up director Alberto Barbera called "the best in 30 years.”