Antonio Conte acknowledged his Chelsea side missed the organisational skills of John Terry as they suffered a first defeat of the season against Liverpool.
First-half goals from Dejan Lovren and Jordan Henderson, the latter's strike a superb dipping effort from distance, proved enough for Friday's visitors to Stamford Bridge, with Diego Costa's subsequent response proving in vain for Chelsea.
Former Italy boss Conte was frustrated by defensive lapses in the build up to both Liverpool goals and was asked in his post-match news conference if the absence of veteran defender Terry, out with an ankle injury, had proven significant.
"I think we missed the organisation [of Terry] in certain situations: free-kicks, throw-ins. You must pay attention," replied Conte.
"In the first half I must be honest, I think that we gave away two goals - the first after a free-kick that they took very quickly and the second after a throw-in, and Henderson received the ball free and shot from long distance, a great goal.
"When you give away two goals in this way, I think it's very difficult because against Liverpool you play with a great team, these are tough games and I think that you must pay attention in every moment, in every single minute of the game, every second, because the details make the difference."
Conte, previously unbeaten as Chelsea manager, was unable to confirm whether Terry will return for Tuesday's League Cup tie at Leicester City.
"I don't know this," said the 47-year-old. "He had an injury in his ankle and I don't know exactly the time that he will take to recover."
David Luiz made a second debut for the club, following his return from Paris Saint-Germain, with Terry unavailable.
"I think he played very well," added Conte of the Brazilian.
