Managers are always at the mercy of their jobs if their teams fail to replicate plans on the drawing board on the field of play.
There are managers who are already on the brink of getting sacked this season following their poor strings of results in all competitions.
Their respective results in the Champions League could prove vital if another result does not go their way.
Here are the three coaches who could be sacked should their teams lose in the Champions League
1. Jose Mourinho
It is obvious that the Manchester United manager could be shown the exit door if his side lose to Spanish side Valencia at Old Trafford.
Firstly, United were held to a 1-1 draw by Wolves in the league and a few days later, they lost to Derby County in the Carabao Cup as well as the weekend defeat to West Ham at the London Stadium.
Former Real Madrid boss Zinedine Zidane has been heavily linked to replace the Portuguese which could happen anytime soon.
2. Thomas Tuchel
Paris Saint-Germain are currently having a great season recording eight wins from eight matches in the French Ligue 1.
But the Parc Des Princes outfit are craving for more than just the performance in the league, the Champions League is their main aim for every campaign, that was why the likes of Neymar and Kylian Mbappe were signed for staggering fees.
The German coach lost their first game to last season's finalists Liverpool and face Red Star Belgrade in a must win match in Paris which could prove vital to Tuchel's job.
3. Leonardo Jardim
Monaco have been disastrous this season in the league and are languishing in 18th on log with just one win in eight matches.
The French outfit were beaten 2-1 by Atletico Madrid at Stade Louis II on match-day 1 and they will be guests to Borussia Dortmund at the Signa Iguna Park on match-day 2.
Anything less than a victory could spell doom for Leonardo Jardim who once qualified the team into the semi finals.
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