Thomas Tuchel questioned Chelsea’s commitment and insisted they need more new signing after a 4-0 defeat by Arsenal in a pre-season friendly in Orlando.
Gabriel Jesus, Martin Odegaard, Bukayo Saka and Albert Sambi Lokonga scored for the Gunners, who were the better side throughout.
Blues head coach Tuchel said: “I am far from relaxed. We were simply not good enough. We were simply not competitive.
“The worrying part is that the level of commitment physically and mentally for this match was far higher for Arsenal than for us.
“It was surely not our strongest line-up,” added Tuchel, who said he “cannot guarantee we will be ready” for Chelsea’s Premier League opener at Everton on 6 August.
Chelsea have made two major signings this summer, bringing in defender Kalidou Koulibaly and England forward Raheem Sterling.
But with Antonio Rudiger and Andreas Christensen having left and Romelu Lukaku loaned back to Inter Milan, and amid doubts over the futures of the likes of Cesar Azpilicueta and Marcos Alonso, Tuchel says there is an urgent need for more additions to the squad.
He said: “I look at the last season and parts of the game where we struggled, then we got sanctioned and players left us, and some players are trying to leave us.
“So we had an urgent appeal for quality players – a huge amount of quality players. We got two quality players but we are not competitive like this.”