Olivier Giroud has blamed the heat and humidity for Chelsea's loss to Kawasaki Frontale.
The Blues were downed 1-0 by their J-League opponents on Friday thanks to Leandro Damiao's late header.
And Giroud admits Chelsea struggled in trying conditions in Yokohama.
He said: I don't know how the Japanese teams do it, it's very humid and very warm.
Our fitness is not perfect but we're working hard."
