Casey Stoner believes Marc Marquez 'felt in some way threatened by me' while the Australian was still at Honda and hinted that this may have contributed to HRC turning down his offer to replace Dani Pedrosa.
After quitting racing at the end of 2012 Stoner took up the role of test rider for Honda and witnessed Marquez emerge to claim back-to-back MotoGP crowns in 2013 and 2014.
When Marquez's Repsol Honda team-mate Dani Pedrosa was forced to pull out of three rounds at the start of 2015 due to injury, Stoner offered to take his place, only to be turned down by Honda for Hiroshi Aoyama.
The two-time MotoGP world champion has now called an end to his test rider deal with Honda and returned to Ducati.
"At Honda I was just an occasional tester and wasn't being used to my potential," Stoner said to Motosprint
. "I loved working with the HRC guys but I think Marc and his crew felt in some way threatened by me and I don't know why. I was just there to test and help.
"I have absolutely no hard feelings towards Honda and I have great respect for Shuhei Nakamoto [HRC vice president], so our relationship will be fine in the future.
"I felt ready [to replace Pedrosa] for Austin. Nakamoto told me he was sorry and that it had been him who made the decision. But I think other people must have put pressure on him for me not to race."
Stoner's new role at Ducati is as a 'brand ambassador and test rider', including an appearance at World Ducati Week from 1-3 July along with 'a selected number of MotoGP tests'.