Les Parisiens played out a 1-1 draw with Saint-Etienne in Pochettino's maiden game in charge, while Brest kept their European hopes alive with a 2-0 win over Nice.
Nearly 18 years after turning out in a PSG shirt for the final time as a player, Pochettino took charge of his first game for the perennial Ligue 1 champions on Wednesday, but it was not the fast start that the Argentine was hoping for.
Saint-Etienne could hold almost any side to a draw in their current form, and Les Verts once again claimed a point from a top-flight fixture as both sides notched up a goal apiece on the night.
Romain Hamouma netted first for Saint-Etienne before Moise Kean scored the first goal of the Pochettino era three minutes later, and PSG managed to climb back up to second with that win following Lille's shock defeat at home to Angers.
However, PSG lost more ground on runaway leaders Lyon after their 3-2 win over Lens on Wednesday evening, but Pochettino's side boast a far better goal difference and just need Les Gones to slip up once - which they could very well do against an in-form Rennes - to get back on their perch.
It is an incredible shame that Pochettino's return to the Parc des Princes will be devoid of the 47,000-strong PSG faithful roaring his name, but the 48-year-old will simply be focused on getting his team over the line against a Brest outfit who can certainly cause problems on the attacking front.
Meanwhile, Brest have epitomised inconsistency during the 2020-21 campaign, but this weekend's visitors to the Parc des Princes kicked off the new year in perfect fashion with a 2-0 victory over a struggling Nice outfit.
Franck Honorat and Steve Mounie got the goals which propelled Olivier Dall'Oglio's men to their eighth victory of the season, and no team outside of the top six has notched up more than Brest's 30 strikes as the season approaches its midway point.
Despite their topsy-turvy form, Brest have only tasted defeat once in their last five league outings and rose to 10th with that triumph after Metz failed to get the better of Bordeaux, and a shock appearance in Europe could be on the cards if Les Pirates can start winning on a regular basis.
However, Dall'Oglio's men possess the third-worst away record in the league ahead of their trip to the capital and have only taken one point from the last nine on offer on unfamiliar turf, although that came in a hard-fought 2-2 draw with Lyon last month.
PSG have eased to victory in their last six meetings with Brest across all competitions, and the Ligue 1 champions have not tasted defeat against their weekend opponents since the 1984-85 campaign.
Paris Saint-Germain Ligue 1 form: WLWDWD
Paris Saint-Germain form (all competitions): WLWDWD
Brest Ligue 1 form: LWDDLW
PSG's medical room is well-occupied at the minute, with star man Neymar still recovering from the ankle injury he sustained against Lyon and compatriot Rafinha out after testing positive for coronavirus.
On a more positive note, Layvin Kurzawa, Alessandro Florenzi and Mauro Icardi could all return here, but the likes of Danilo Pereira, Presnel Kimpembe and Leandro Paredes are still struggling with various injuries.
Wholesale changes on PSG's end are unlikely given their plethora of absentees, but Julian Draxler is vying for a start after making his return from a lengthy layoff.
Dall'Oglio may be tempted to bring Jean-Kevin Duverne back into the defence, but the visiting manager is expected to keep faith in the same XI from the midweek win over Nice.
Paris Saint-Germain possible starting lineup:
Navas; Dagba, Marquinhos, Kehrer, Bakker; Gueye, Herrera, Verratti; Di Maria, Kean, Mbappe
Brest possible starting lineup:
Larsonneur; Pierre-Gabriel, Chardonnet, Herelle, Perraud; Faivre, Lasne, Belkebla, Honorat; Mounie, Cardona
We say: Paris Saint-Germain 3-2 Brest
Brest's effervescent attacking crop can certainly do some considerable damage to PSG's ravaged backline, but the visitors' defensive frailties are evident despite Wednesday's much-needed clean sheet. Les Parisiens boast an incredible record in this fixture and Pochettino will be desperate to get up and running as quickly as possible, so we expect the champions to prevail in what should be a fascinating contest.