Hamilton heads into Sunday’s Monaco Grand Prix with a 17-point championship lead over Sebastian Vettel following consecutive victories.
While Hamilton was fortunate to win in Azerbaijan last month, the 33-year-old Englishman returned to his dominant best with an emphatic victory at the last round in Spain a fortnight ago.
The Mercedes driver is on the back foot here in Monte Carlo with Red Bull and Ferrari the teams to beat.
But Rosberg, who triumphed over Hamilton to win the 2016 championship before retiring only days later, believes his former team-mate remains the class of the F1 field.
The sport’s former overlord Bernie Ecclestone claimed in Baku that Hamilton had lost his edge, but Rosberg, here in Monte Carlo this weekend, said: “If I look at the race in Barcelona, I saw the best Lewis I have ever seen.”
Rosberg, 32, called time on his motor racing career after ending his losing streak to Hamilton by clinching the championship at his final race in Abu Dhabi 18 months ago.
His shock decision brought the curtain down on a toxic rivalry with Hamilton, but the pair have failed to patch up their differences.
Rosberg is now a shareholder in the all-electric Formula E series while also working as a part-time pundit for Sky Sports and has no plans to return to the sport.
“It has been a nice transition and I am happy with the way things have gone and the decisions I have taken,” Rosberg added. “I can look back at it and I am very happy with life. There is no way back to F1 and for me that is it.”
Daniel Ricciardo will line up on the starting grid on Sunday firmly in the belief that Red Bull owe him a victory on F1’s most famous streets.
All eyes are on Red Bull at the principality after Ricciardo cemented their status as the pre-race favourites by posting the fastest lap ever recorded in Monte Carlo en route to completing a practice double on Thursday.
Ricciardo, 28, is yet to open his winning account at his adopted home, but should have taken to the top step of the podium here two years ago only for his pit crew to botch his stop.
He went in, Red Bull were not ready with his new tyres, and the ensuing delay allowed Lewis Hamilton to steal the victory. Naturally, the usually laid-back Ricciardo was seething.
“Yes, I do feel I am owed a win,” Ricciardo said.