Chelsea will start the second half 1-0 down on the night against Sparta Prague in the second leg of their last-32 encounter in the Europa League.
Sparta's away goal means that the tie is finely poised at 1-1 on aggregate as both sides look to reach the last 16 of the competition.
Fernando Torres had three early chances for the hosts as they started with plenty of attacking intent.
The Spaniard shot over the crossbar with his first two efforts before a third saw him head high and wide.
Sparta then struck with 17 minutes played when Vaclav Kadlec found David Lafata, who tapped home from six yards.
The visitors were on the attack soon after, but Tomas Prikryl's near-post effort was scrambled away by Petr Cech.
Marek Matejovsky then blasted his effort well over before Juan Mata's shot was expertly tipped over by Tomas Vaclik in the final moments of the half.
