And there are those who are in awe of the revitalized one, the pragmatic Portuguese whose measured words always have a purpose. He is the man who would peacock on touchlines and in press conferences even before his greatness had manifested itself, achieving success with a snarl and a swagger.
You are either rooting for one or the other. Never both. For not only are Jurgen Klopp and Jose Mourinho chalk and cheese, but leaders of clubs whose rivalry has become a tribal loathing.
Both managers have been at their respective clubs long enough -- Klopp celebrated his second anniversary at Anfield last weekend while Mourinho is in his second season at Old Trafford -- to know that Saturday's Premier League contest between Liverpool and Manchester United is more than a football match.
The rivalry between English football's two most successful teams is a lesson in history. Rifts run deep. Feuding fans never forget.
In April 1992 a young Ryan Giggs was approached by a Liverpool fan as he was leaving Anfield. The supporter asked the curly-haired winger for his autograph and the Welshman obliged, writing his name on a piece of paper, only for the fan to tear it up in front of his face.
Indeed, the last time a player moved between the two clubs was in April 1964 when Mancunian Phil Chisnall joined Liverpool.
This intense contempt hasn't always been so -- in 1915 a handful of players from both clubs were banned for conspiring to fix a match so that United were not relegated, but the bitterness between the fans intensified during the 1980s and though Liverpool versus United may now be a global affair, and the main characters in this perennial mean-spirited play ever-changing, the antipathy which surrounds this fixture remains.
For Klopp and Mourinho, however -- managers who have exchanged barbed words in the past -- the weekend's clash goes further than hatred and history.
Bringing back the glory days
Engaging and charismatic, Klopp and Mourinho are leaders charged with the same mission: to bring back success, bring back the chutzpah, to two footballing institutions that have enjoyed better times.
On Saturday, onlookers will find out which manager is closer to achieving his objective.
United's start to this Premier League campaign suggests Mourinho's men are title contenders, which would continue the former Real Madrid and Inter Milan boss' record of winning a league title in his second season at every club he has managed.
With Liverpool seven points behind joint leaders United and...
Read More: Liverpool vs. Manchester United: Jose Mourinho and Jurgen Klopp have a shared mission