Nico Rosberg says Lewis Hamilton excels in wheel-to-wheel battles in a way that ensures any incidents are "never really his fault" and conceded the breakdown of their friendship was "tough".
Six-time Formula One world champion Hamilton spent four seasons alongside Rosberg after joining Mercedes in 2013.
The Briton won world titles in 2014 and 2015 but Rosberg got the better of him in 2016, a year where the team-mates' relationship, which had been growing increasingly tense, broke down completely.
Rosberg called time on his career after his world championship success in a year that included an infamous crash between the two at the Spanish Grand Prix.
He praised the ability of Hamilton, who has gone on to add three consecutive drivers' titles with Valtteri Bottas as his team-mate, when it came to their scraps on the track.
"The guy is phenomenal in a wheel-to-wheel battle," Rosberg said in an interview for Heineken with David Coulthard.
"It's unbelievable how he positions the car so smartly. Whenever I would go up against him, hold my own and fight back, he would always manage to stay in the grey area.
"He would be so skilled at keeping it in the grey area, and never really making it 100 per cent his fault. That was a huge strength of his, one of the huge strengths he has of the many.
"Sometimes I would just straightaway jump over the grey area into the black area, which is not allowed."
Rosberg insisted he was not daunted by Hamilton's arrival as his team-mate, having spent three years with Mercedes and won just one race before his old friend's move from McLaren.
"I knew how good Lewis was because I raced him in go-karts for many years and I knew that he was extra special," added Rosberg.
"I was like, okay, done, I've conquered the most difficult guy out there [Michael Schumacher] and then they say Lewis is incoming.
"There wasn't any negativity in my mind, I was looking forward to the challenge because he was a world champion. I was able to play level field with Lewis all the way through.
"In 2013, it was still pretty much easy going because we weren't fighting for race wins, and we used to be best friends, so that was a decent start.
"But then going into 2014, that's where you noticed because once you are fighting for race wins and championships, there is so much at stake.
"Your dream is at stake. Both of us dreamed of winning the world championship with Mercedes. It's so big.
"It's hard to make compromises, and it's the friendship that gets compromised, in return for winning races. It just went small step by small step, and it just builds up. It was tough."