Liverpool - The last time Thomas Tuchel went to Anfield, he was in charge of a Borussia Dortmund side who were dumped out of the Europa League after a stunning Liverpool comeback.
On Tuesday, he returns with Paris Saint-Germain (PSG) looking to finally get one over Jurgen Klopp in one of the most enticing ties in the Champions League group phase.
Klopp and Tuchel are the highest profile German coaches around today, with both men having followed strikingly similar paths at home before taking up jobs with two of Europe's biggest names.
At 51, the genial Klopp is six years Tuchel's senior and his CV features two Bundesliga titles and two Champions League finals, while his opposite number was appointed by PSG in May despite having only won one German Cup as a coach.
Klopp has won eight, and lost just one, of 12 previous meetings with Tuchel. He is quick to play down that record, however, pointing out that Tuchel was not in charge of a side containing the likes of Neymar and Kylian Mbappe before.
"When I was at Dortmund I had a pretty strong side and he was at Mainz, he did an outstanding job there so it's not really fair to bring that up when you talk about the records," Klopp said on Monday.
"He is an outstanding coach, I really thought it was a smart decision of PSG to sign Tuchel."
The svelte 45-year-old is the man PSG's Qatari owners are hoping can finally lead them to Champions League glory, despite his past experience amounting to one quarter-final exit with Dortmund in 2017.
A year before that, at the same stage of the Europa League, Dortmund were 3-1 up at Anfield before losing 4-3.
That was part of the learning curve for the economics graduate Tuchel, a native Swabian like Klopp, and also a defender during his playing days.
While Klopp was a stalwart for Mainz on the field before becoming coach in 2001, Tuchel's own playing career was cut short by injury.
But since moving into coaching he has followed in the footsteps of "Kloppo" - taking over at Mainz in 2009 a year after Klopp's departure for Dortmund, and then directly replacing him at the Signal Iduna Park in 2015.
The two men got their coaching badges together in Cologne in 2006, but it is the differences between them that have stuck with Erich Rutemoeller, their instructor.
Klopp "was more motivated than anyone and was especially interested in the psychological aspect," Rutemoeller told Le Parisien, while stressing the more introverted Tuchel's great respect for Pep Guardiola.
"When I read that he spent a whole evening talking about tactics with Pep Guardiola, a few years ago in Munich, moving around the salt and pepper, I thought to myself: 'He's not changed'."
As for a Tuchel win against Klopp, you have to go back to April 2010, when Mainz beat Dortmund 1-0 at their old Bruchwegstadion thanks to an Adam Szalai goal.
In two years at Dortmund, Tuchel could not repeat Klopp's successes, his path to the Bundesliga title blocked by Guardiola's Bayern Munich. But he enjoyed the greater success at Mainz, leading them into Europe in 2011.
Liverpool's start to this season has raised hopes of a genuine Premier League title challenge, with Klopp overseeing five wins out of five.
But PSG rock up with a perfect domestic record too, and Tuchel has become the first ever coach of the club to win his first five Ligue 1 matches.
"For this kind of team with unbelievable individual quality, you still need a manager who can teach or educate them in playing together and they brought in one of the best I know," Klopp added.
"That makes them quite a big challenge for us. Individual quality mixed with a really good manager makes it a threat."