Lewis Hamilton has delivered an ominous warning to his rivals by declaring he is on another level ahead of the new Formula One campaign.
Hamilton, 35, is gearing up for his assault on matching Michael Schumacher's record haul of seven world championships.
The British driver has spent much of the off-season in America, but returned to the Mercedes' factory in Northamptonshire for the first time this year on Tuesday.
"It has been an incredible winter," said Hamilton in an online message. "I have spent a lot of time with family and friends.
"I would say probably one of the best times has been with my dad, and secondly, the training has been different this year.
"The feeling I have, both physically and mentally, is on another level compared to last year. That is a real positive."
Hamilton will get his first taste of the Mercedes machinery he hopes will allow him to equal Schumacher in a behind-closed-doors team event at Silverstone on Friday.
Max Verstappen put this year's Red Bull through its early paces during a filming day at the Northamptonshire race track on Wednesday, less than 24 hours after Charles Leclerc and Sebastian Vettel unveiled their new Ferrari in a theatrical team launch in Italy.
The trio pose the biggest threat to Hamilton's title defence which will start with six days of winter testing in Barcelona before the campaign gets under way at the Australian Grand Prix on March 15.
"I know you guys are gunning for title number seven but we have to take it one step at a time," added Hamilton.
"We have no idea where we are going to stand compared to everybody else, so we have to be more efficient in our test programme this year, particularly as we have less testing time. We still have a lot of work to do."
Hamilton, whose current contract expires at the end of the season, is in negotiations with Mercedes over a new deal which could be worth up to a staggering £60million-a-year.
Ferrari distanced themselves from a move for Hamilton on Tuesday, by claiming their priority is to keep Vettel alongside Leclerc in 2021.