Despite being seven points clear at the top in France, the defeat to Dijon last weekend was the club's third in the league since August, highlighting the fact that things are far from perfect at the Parc des Princes.
Indeed, given that Niko Kovac was recently sacked by Bayern Munich after just two league defeats, it could be said that the main thing keeping Tuchel relatively safe is the comparative weakness of PSG's domestic opponents.
Some might also say that the defeat last weekend, much like the one to Stade Reims, came against a starting XI that was picked on the basis of resting certain players for the Champions League.
After all, it is against this metric of success in Europe, as opposed to winning the Ligue 1 title, that Tuchel will be judged by the club's ownership, who are desperate to see the club claim its first European crown under the watch of Nasser Al-Khelaifi.
Yet with 13 days separating this game from PSG's next outing, supporters are likely to see their manager field a strong starting XI in an attempt to return to winning ways in the league.
In Brest, however, PSG come up against a team that is enjoying a superb return to the top flight of French football after being relegated in 2013.
Incredibly, the newly-promoted side has only lost three times so far this season - the joint fewest in the division after 12 games, matched only by PSG and Marseille.
Such a statistic underpins Brest's guiding principle this season, which revolves around an enormous amount of collective discipline and a supply of energy that they have worked on consolidating for some time.
A recent run of victories over Metz, Angers and Dijon served to underline what this team was about, with Brest winning those games 2-0, 1-0 and 2-0 respectively - keeping the game tight while doing enough to claim a victory.
A similar approach against PSG, whereby they maintain a low block and minimise space, could serve as the perfect way to frustrate the French champions and claim what would be their biggest result in years.
Recent Brest form: LWWWWL
Recent Paris Saint-Germain form: WWWWLW
Meanwhile, PSG continue to be without Neymar, who is still battling a hamstring problem that has plagued the Brazilian for almost a year.
Brest possible starting lineup:
Larsonneuer; Belaud, Castelletto, Chardonnet, Baal; Autret, Diallo, Belkebla; Cardona, Mendy, Grandsir
Paris Saint-Germain possible starting lineup:
Navas; Dagba, Silva, Kimpembe, Diallo; Marquinhos, Gueye, Verratti; Di Maria, Mbappe, Cavani
We say: Brest 1-3 Paris Saint-Germain
With Tuchel fielding a strong team that will want to assert its presence early on against Brest, the front three of Edinson Cavani, Kylian Mbappe and Angel Di Maria will ultimately serve as the main difference between the two sides in what nonetheless promises to be a competitive affair.
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