Quartararo made his MotoGP debut in 2019 alongside Morbidelli at the Yamaha SRT squad before the Frenchman was promoted to the works teams from the start of the 2021 season, when he claimed his first and so far only title.
Morbidelli was reunited with Quartararo in 2022, when the Italian also secured a factory ride. The duo raced together until last year when Morbidelli lost his ride and was replaced by Rins.
The Italian, a member of Valentino Rossi's VR46 Academy, will partner with last year's runner-up Jorge Martin at Pramac Ducati.
Morbidelli was absent from the first pre-season test at Sepang last week after an accident he suffered while training at Portimao last month. He will also miss the Qatar test that concludes the pre-season before the racing begins at Losail on 8-10 March.
During their four years as team-mates, the distance between Quartararo and Morbidelli was evident, partly because of their different personalities with the Frenchman much more of an extrovert than the Italian.
At Sepang, Yamaha's star rider shared the garage with Rins, whom he always said he feels much closer to, not only because they both live in Andorra, but also on a personality level.
"With Alex, I felt very good," Quartararo told Motorsport.com during a break for running on the final day of testing in Malaysia.
"Basically I have spoken and had more contact with him in a test than with Morbidelli in four years. As it is, that's what I think and that's the reality."
He added: "It's nice to be able to go to the other side of the garage and talk naturally. Before, when Franco was there, I didn't dare.
"With Alex, we have this rivalry, he wants to beat me and I want to beat him. But I'd rather beat him by being first and him second than by finishing 10th and 11th.
"We have a riding style which, although not the same, means that the problems we have are the same."
Quartararo ended the Sepang test with a best lap that left him eight tenths of a second off the quickest rider, Francesco Bagnaia, and four tenths clear of Rins.
