When Jose Mourinho left Chelsea the first time around, more than six years ago, Brendan Rodgers was the club's reserve-team manager with a page in the matchday programme and a profile that did not extend much further than the gates of Cobham.
There are some over the years who have overstated their closeness to Mourinho, or claimed tenuous status as one of his coaching prodigies, but there is no doubting that Rodgers was the real deal.
"One of my best friends in the game," was how Mourinho referred to the Liverpool manager this week, and with none of the excruciating forelock-tugging that once accompanied his eulogies to Sir Alex Ferguson.
There is exactly 10 years between the ages of Rodgers and Mourinho – they share the same birthday, January 26– which is not far from the 11-year difference between Mourinho and his mentor, Louis van Gaal.
Of course, like Mourinho, Ulsterman Rodgers has ploughed his own furrow, but there is no question that the association has been a help and that the friendship between the two is genuine.
Which means that tomorrow's game between Chelsea and Liverpool, the Premier League match of the weekend, takes place amid a very different atmosphere between the benches to that during Mourinho's first stint at the club.
The relationship between Mourinho and Rafa Benitez became toxic, after a reasonably friendly start, and never recovered. The two sets of supporters dislike each other even more.
In the aftermath of victory over Swansea on Boxing Day, Mourinho was invited to analyse Rodgers' impressive start to his second season and he described him as "good" (twice) and "intelligent" which even by his revised standards of behaviour was striking.
Of course, there was the dagger thrust about the rest time afforded to Liverpool because of their non-participation in Europe, but it was never going to be all one-way.
How quickly the willing apprentice finds himself in a position to challenge the master.
The last time Mourinho won a Champions League title, with Internazionale in May 2010, Rodgers was still out of work after his bruising six months as manager of Reading.
Since he took the Swansea job in July 2010 his progress has been remarkable, justifying the leap of faith Chelsea took recruiting him from Reading's academy nine years ago and his subsequent promotions under Mourinho.
He was hired by Neil Bath, Chelsea's academy manager, and was one of the young coaches who fastened on rapidly to Mourinho's way of working.
Rodgers soaked up the knowledge and impressed Mourinho with his willingness to learn.
Were Liverpool realistic title challengers as the season approaches its half way stage?
"I think they are," Mourinho said. "Because they are good. Because Brendan is good. Because they have time to prepare the team tactically.
"Because they are not involved in the heat of the knockout situation in the Champions League or even Europa League.
"These players are going to play 60 matches for Chelsea. Liverpool will play 40 matches. It's a big difference. Quality plus ambition plus this advantage, so yes.
"The manager is one of my best friends in the game, so no rivalry.
"Full respect for a team with the history like Liverpool. He's doing fantastically."