Former Chelsea star Emmanuel Petit says this week's clash with Leicester City in a must-win.
Wednesday's loss to Liverpool made it two losses from the first two games of the season for Frank Lampard's men.
They will face Leicester at Stamford Bridge this weekend, and Petit says the Blues must collect all three points.
He told Paddy Power: "The game against Leicester on Sunday is must-win for Lampard. They have to win it, it's so important for the players and their confidence but also for Lampard's confidence too. After United I believe the players were thinking about what a big loss Eden Hazard is, and how they would compete without replacing him.
"But after the Super Cup and a win against Leicester can turn that confidence around, they have a quality team with quality players and Lampard is using youth too which is good to see. Jorginho had by far his best game in a Chelsea shirt since he arrived and to do well those performances need to be kept up.
"Failure to beat Leicester will mean people will start asking questions of Lampard, it will put much more pressure on him and on the players and questions will be on the table about whether Lampard is right for the job. That in turn puts more stress in the dressing room and more trouble for the manager.
"The pressure will be so huge on their shoulders if they don't get the result, so they have to start well and win convincingly. It'll buy them time to work on the team and bring back confidence, but after the Liverpool game I would say they have good reason to believe they will win. If they keep playing like that, they will games and that's a fact.
"For me, they have the players to do well in the Premier League this season, they will be one of the teams to beat – though I can't say the same for the Champions League. Lampard received some criticism from Jose Mourinho when they played Chelsea, but it was his job to comment and be honest about what he felt.
"He will realise that he will get a lot of opinions now and people telling you what you should and shouldn't do, people pointing in your face and telling you that you are wrong, but it's the same for all big clubs. You will face criticism as Chelsea manager."