Following his retirement from Sunday's United States Grand Prix, Daniel Ricciardo's current boss, Christian Horner, couldn't allow the opportunity to slip by without taking another dig at the Australian's future employers.

"I'm sure he'll be having a word with his future employers about it, " said Horner, having revealed that following his early retirement from the race the Australian had punched a hole in the wall of his room in the Red Bull unit.

While the exact cause of Ricciardo's retirement isn't clear, and may not be entirely down to Renault, the Australian remains undaunted by his decision to switch teams and insists he was always aware that he wasn't jumping straight into a championship challenging car.

"When I signed, I knew that there was work ahead," he admitted, "but I know that they're putting a lot of effort into making things better and expanding a lot of departments and trying to make '19 stronger and '20 and whatever.

"Yeah, the way the last few races have been this year, obviously, it would be nice to see them improve every race and whatever but I honestly don't look into it too much yet.

"'19 is a new car and it's going to be a fresh start again, so I'm not spending too much energy on that at the moment. Obviously, all I can do is, once my year's done is try to be fully immersed into it all and try to help as much as I can and see how things go from there."

While Red Bull has vetoed Ricciardo's hopes of driving the Renault in the post-Abu Dhabi test, there is speculation that a reshuffle of technical bosses that could rival anything seen on the driver market this year, might well have been in the back of the Australian's mind when he made the move, Renault having secured a number of high-profile signings in the last year.