Jorge Lorenzo has quipped that Cal Crutchlow is crash-prone and can test how hard Yamaha's bikes are when he joins the Iwata marque.
Crutchlow is replacing Lorenzo in that test role next year, with the latter's latest barb coming after another critical remark which he made on social media in the past week.
Then, the three-time premier class champion seemingly argued that being replaced by the three-time premier class race winner was akin to “exchanging gold for bronze”.
When that was put to Crutchlow, he declared that the Spaniard's titles, including two in the 250cc class, do not necessarily mean he is a good test rider.
While the Briton seemed not especially fazed, Lorenzo did not hold back when asked about those comments after he invited questions on his Instagram page.
“Saying that I'm not a good tester is like saying that the Earth is square,” he wrote.
“Engineers and riders who shared the box with me in Yamaha and Ducati know how good I am in developing the bike and helping them to make it faster.
“If we only talk about numbers, it's a fact that after I left both teams, the number of wins per season decreased.
“About Cal, he has been one of the riders with less wins and more crashes in the last 10 years.
“I think he will be a good tester. To test how hard the bike is.”
Lorenzo was also asked how he ranked the best of his sport, and declared that he is the fifth-greatest of all time, behind Valentino Rossi, Marc Marquez, Giacomo Agostini, and Mick Doohan, respectively.
Marquez, however, is his pick as best of the last decade, ahead of himself and then Casey Stoner.
Race start is due on Monday at 01:00 AEDT.