Thomas Tuchel says that his Chelsea side produced 'one of their worst first half performances' against Real Madrid on Wednesday night.
On another day, Los Blancos could have scored more than twice during the opening period at Stamford Bridge, instead having to make do with a 2-1 half-time advantage.
Nevertheless, the Spanish giants were deserved victors in London, leading to Tuchel heavily criticising his team after the full-time whistle.
Speaking to BT Sport, the German said: "It is a heavy loss. It was one of the worst first halves that I saw from us here at Stamford Bridge. Individually and as a team it was by far not enough. It was far from our standards and then you lose games.
"Passing, where we passed, how we passed when we passed, when we attacked, the ball possession game, first half was so from any standards that we set ourselves that we cannot complain when we lose. We had 16 shots in the second half. You can always come back and win it but when you kill the game by yourself after 45 minutes it is harder and harder.
"No, we don't have to go to Madrid we have to go Southampton and it is very important to process this. It is crucial that we go to Southampton. If we keep playing like this we will lose at Southampton and then we will get hammered at Bernabeu."
Chelsea have now conceded seven goals in two home matches, the other four coming against Brentford on Saturday, and those strikes have all come within an 86-minute period.