Having won all eight of their matches in this year’s competition and with one of the most valuable squads in world football, Chelsea entered this match as heavy favourites to progress.
Legia, though, came into the clash with five Conference League clean sheets to their name this term, the highest in the tournament, and they proved difficult to break down in the opening 45 minutes.
In fact, they managed more shots than their illustrious opponents before the half-hour mark, with Luquinhas and Ryoya Morishita firing off-target just as Christopher Nkunku did at the other end.
As the game approached half-time, the Blues had more joy in the final third. Kacper Tobiasz was the first goalkeeper to be called into action, pushing Kiernan Dewsbury-Hall’s curling effort past the post, while Nkunku went close with a header.
Dewsbury-Hall then wasted a fantastic opportunity on the brink of the interval, nodding wide when unmarked in the box as he struggled to get enough power or direction on his shot.
After the break, Chelsea flew out of the blocks, and within five minutes, they were two to the good.
Dewsbury-Hall had already headed over by the time Reece James’ shot was saved by Tobiasz, but Tyrique George was one hand to tap home the rebound for his first ever Chelsea goal.
The visitors continued to set the tempo, and before long, they doubled their lead when Noni Madueke stroked home from close range.
Jadon Sancho was next to try his luck, forcing Tobiasz into another stop.
Dewsbury-Hall will have been disappointed not to come away with a goal after firing another effort over the crossbar midway through the second half.
Nkunku saw another effort saved by Legia’s increasingly busy shot-stopper, and he was subsequently denied a goal once more when his penalty was saved after Dewsbury-Hall was felled by Patryk Kun in the area.
Enzo Maresca’s men didn’t have to wait long for another goal, though, as Madueke was on hand to sweep Sancho’s low cross over the line.
Filip Jorgensen needed to be alert to keep out Kun’s late strike, but, all in all, it was all too easy for Chelsea, who will feel they are well on their way to qualification for the semi-finals.
Legia, meanwhile, will feel they did not do themselves justice in their first European quarter-final for 29 years. They have it all to do at Stamford Bridge next week.
Flashscore Man of the Match: Noni Madueke (Chelsea)