Noni Madueke scored two goals off the bench as a strong second-half showing secured Chelsea a 3-0 win against Legia Warsaw on Thursday.
The Blues had 75 per cent possession and fashioned nine shots to the hosts' three, but could not find a way through in the first half.
Kiernan Dewsbury-Hall's curling effort was expertly pushed away by goalkeeper Kacper Tobiasz, and Rafał Augustyniak did well to stop Christopher Nkunku from turning the ball home from close range.
At the other end, Max Oydele played a delightful through ball to find Ryota Morishita but the Japanese forward couldn't keep his effort on target when in a good position.
Maresca's half-time team talk seemingly worked wonders as 19-year-old Tyrique George scored his first goal for the club after Reece James' shot wasn't held by Tobiasz in the 49th minute.
It was 2-0 just eight minutes later when Jadon Sancho found substitute Madueke in the box, and the winger finished with aplomb.
Mere moments after Nkunku failed to convert he penalty he won, Sancho set up Madueke again from close range to make it 3-0 with 16 minutes remaining.
Patryk Kun brought a great reaction stop out of Filip Jorgensen at the death as Chelsea took a hefty advantage into the second leg of this Conference League quarter-final tie.
GOAL rates Chelsea's players from Marshall Józef Piłsudski Legia Warsaw Stadium...
