Thomas Tuchel questioned the commitment of his Chelsea players and admitted they were "simply not good enough" in their heavy friendly defeat to Arsenal on Saturday.
The Blues were thumped 4-0 by Premier League rivals Arsenal at Camping World Stadium in Orlando in the final game of their pre-season tour of the United States.
Gabriel Jesus, Martin Odegaard, Bukayo Saka and Albert Sambi Lokonga were all on target for the Gunners, who looked far sharper in front of the 64,000 watching spectators.
And with the new season just two weeks away, Chelsea head coach Tuchel is worried about what he saw from his side.
"I think we deserved to lose – which is fair enough – because we were simply not good enough," he said.
"We were absolutely not competitive. The worrying part is the level of commitment, physically and mentally, was not the same – it was far higher for Arsenal than us.
"We can argue they played with I think their strongest line-up; they've had now together several weeks and for more than one year.
"They've strengthened their line-up, played the same structure, and this is the line-up they'll try to start Premier League games.
"It was not our strongest line-up and this is part of an explanation, but only a little part. The other part is worrying."
First-team regulars Edouard Mendy, Reece James, Jorginho and Mason Mount started the game, while new signings Raheem Sterling and Kalidou Koulibaly also featured.
Chelsea were also beaten on penalties by MLS side Charlotte FC earlier in the week after a 1-1 draw in normal time, which followed on from a 2-1 win against Club America.
The Blues round off their pre-season programme away at Udinese next week before facing Everton in their opening Premier League game on August 6.
Tuchel has made clear he wants to further strengthen his squad before that trip to Goodison Park, with Jules Kounde reportedly close to joining from Sevilla.
"The analysing of the season does not change because of this game," Tuchel said when asked about the need to bring in more new signings.
"Unfortunately, it proved my point and the last week proves my point. I would prefer to not be right and I did everything to prove myself wrong.
"But at the moment I feel I was right when I look at the last season and at the parts of the game where we struggled and how we struggled.
"We got sanctioned and players left us, we know that some players are trying to leave us, and this is where it is.
"We've got two quality players – that is no doubt – but we are not competitive like this and unfortunately we could see it today."
Chelsea finished third in the Premier League last season, a distant 18 points behind runners-up Liverpool and 19 behind champions Manchester City.
Tuchel, who was not prepared to use fatigue as an excuse for the Arsenal loss, accepts his side cannot realistically think about making up the gap on the top two.
"At the moment, given the last two weeks, given our last week and given the game today we should not mention the two teams in front of us," he said.
"We got absolutely beaten by a team that does not play Champions League next season, that is behind us. And it seems at the moment far ahead of us."
Tuchel added: "I am a huge fan of a strong pre-season for everything: for the atmosphere, for the feeling, for the performance, for the belief.
"We need to find solutions. We fly home now and then we have one-and-a-half days only and Tuesday afternoon we need to present solutions.
"We need to present actions. We, me, the coaching staff, together with our team to stand up again and find a way through this because it hurts at the moment."