When Monaco led Paris Saint-Germain 2-0 just 18 minutes into the first leg of their Champions League play-off tie last week, few could have foreseen Sebastien Pocognoli's men being relieved to lose by a single goal at full-time.But Desire Doue led a PSG fightback after replacing the injured Ousmane Dembele from the bench, scoring twice and playing a key role in creating another goal for Achraf Hakimi. Monaco also had Aleksandr Golovin sent off in the 48th minute and faced 19 shots in the second half alone, with PSG having plenty of opportunities to kill the tie off.But the European champions were unable to do so, and though they are big favourites ahead of Wednesday's return leg at the Parc des Princes, Monaco remain alive in the tie.Here, we preview the match by delving into the best Opta insights surrounding the key players and storylines to watch.What's expected?Ahead of Wednesday's second leg, the Opta supercomputer assigns PSG a 91% chance of reaching the round of 16, with Monaco only advancing in 9% of scenarios.Luis Enrique's side won the second leg in 70.8% of the supercomputer's pre-match simulations, with 16.6% being drawn.Monaco have a 12.7% chance of victory, which would, as a minimum, take the tie to extra time. PSG have won five of their last seven games against Monaco in all competitions (one draw, one loss), while on home soil, they have only lost one of their last 10 (six wins, three draws), a 2-0 defeat in 2020-21.And their record is even better outside of Ligue 1 play, with PSG winning 13 of the last 14 such matches against Monaco (one draw). Six of those wins were in the Coupe de France, three each came in the Trophee des Champions and Coupe de la Ligue, while the other was in the first leg of this tie.PSG are also the only club in Champions League history to have a 100% win ratio against teams from the same nation as themselves, having beaten Brest 3-0 and 7-0 last term before their victory last week.PSG to rue missed opportunities?Two early goals from Folarin Balogun last Tuesday put PSG on the back foot in this tie, as their Champions League title defence threatened to unravel in spectacular fashion.In the end, Luis Enrique's side may have felt frustrated at leaving the Stade Louis-II only one goal ahead, such was the level of their dominance.Helped by Golovin seeing red for scraping his studs down Vitinha's leg, PSG finished the game with 30 shots and 80.4% possession.That is the highest possession share recorded by any team that had 30 or more shots in a Champions League match since Opta data collection began in 2003-04.It was also the highest possession share any team had achieved in a Champions League knockout game since Barcelona had 82.5% in the second leg of their semi-final defeat to Chelsea in 2012. Seven saves from goalkeeper Philipp Kohn helped to keep Monaco in the tie, with Khvicha Kvaratskhelia (eight shots worth 0.55 expected goals), Vitinha (five shots, 0.98 xG), Joao Neves (four shots, 0.37 xG) among the PSG players to misfire. And any nerves among PSG's supporters will not be helped by the news that Ballon d'Or winner Dembele is unlikely to start Wednesday's game after limping off in the principality. However, there have been 18 previous instances of PSG winning the first leg of a two-legged major European knockout tie away from home, and they have only failed to progress on one occasion.That elimination came in the last 16 of the Champions League in 2018-19, when they were eliminated on away goals by Manchester United, losing 3-1 at home after winning 2-0 at Old Trafford. Can Monaco replicate Ligue 1 fightback?Monaco did PSG a major favour last time out in Ligue 1, launching a stirring fightback to defeat their title rivals Lens 3-2 having trailed 2-0 at the hour mark.Goals from Odsonne Edouard and Florian Thauvin had Lens in the ascendency in Saturday's match at Stade Bollaert-Delelis, only for Balogun, Denis Zakaria and Ansu Fati to score within the space of 10 minutes to flip the script.It was the first time Monaco had won a Ligue 1 match after trailing by two goals since May 2022 (4-2 versus Brest), and the first time Lens had lost from such a position since March 2025 (3-4 versus Le Havre).Monaco have now won back-to-back Ligue 1 matches (against Nantes and Lens), as many victories as they managed in their previous 11 (two draws, seven losses), so they should not be short on confidence. But overhauling their first-leg deficit to defeat the reigning European champions will be even more of an uphill battle.There have been seven previous instances of Monaco losing the first leg of a major European knockout tie on home soil, and they have been eliminated on all seven occasions.PLAYERS TO WATCH Paris Saint-Germain – Desire DoueDoue was named on the bench for the first leg following a poor run of form, but he was called upon in the 27th minute after Dembele limped off.The 20-year-old only needed one minute and 59 seconds to get on the scoresheet, the fourth-fastest goal scored by a substitute in the Champions League this season.After striking again in the second half, Doue has netted six goals in his last six Champions League appearances, with all of his goals coming in braces (also versus Inter and Bayer Leverkusen).His next goal will be his 10th in the tournament, and should it come in this match (at the age of 20 years and 267 days), he would become the youngest PSG player to reach 10 goals in major European competitions (currently Kylian Mbappe – 20 years, 306 days).Monaco – Folarin BalogunBalogun has netted five goals in his last six Champions League appearances, while his five goals this season are the most by a Monaco player since 2016-17, when Radamel Falcao got five and Mbappe scored six. He also has four goals in his last five games in all competitions against PSG. He has only scored more goals against Lens (five) in his professional career.