Willian starred with two goals as Chelsea warmed up for a season-defining few weeks by easing into the FA Cup quarter-finals by thrashing Hull City 4-0 at Stamford Bridge on Friday.
Just four days before facing Barcelona in the first leg of their Champions League last 16 tie, Chelsea boss Antonio Conte named a much-changed side with Thibaut Courtois, Cesar Azpilicueta, N'Golo Kante and Eden Hazard not even included in the Italian's squad.
But they still had too much quality for the Championship strugglers as two great strikes from Willian added to goals from Pedro Rodriguez and Olivier Giroud's first for Chelsea put the hosts 4-0 up by half-time.
Conte made seven changes in all from the side that beat West Brom 3-0 on Monday to ease the mounting pressure on his job.
Once again the Chelsea support showed their backing for the former Juventus boss, but more challenging tests lie ahead in their bid for Champions League glory, and a place back in the competition next year via the top four of the Premier League should they fall short.
Barca's visit to the Bridge on Tuesday is followed by consecutive trips to Manchester United and Manchester City on league duty before the return leg at the Camp Nou on March 14.
Willian did no harm to his case to start against the Catalans with a stunning all-round display capped by his two goals.
The Brazilian opened the scoring after just two minutes as he jinked inside onto his weaker left foot but still produced a fine curling shot into the far corner.
Giroud stabbed a good opening inches over before just failing to get on the end of a Danny Drinkwater cross after more great work by Willian in the build-up.
Willian was the creator once more when Pedro passed up a huge chance as David Marshall got down well low to his left.
But it seemed only a matter of time before a second goal arrived and it was the former Barca duo Cesc Fabregas and Pedro who combined as the midfielder's lofted pass freed Pedro in behind the Hull defence to slot past Marshall.
Willian showed he is capable of scoring from range off either foot as his low drive cushioned the post on its way past Marhsall moments later for his 10th goal of the season.
Giroud then cut a relieved figure when he tucked home debutant Emerson Palmieri's low cross to round off a first 45 minutes to forget for the visitors.
Hull had the chance to salvage some pride early in the second-half when Fabregas tripped Liverpool loanee Harry Wilson inside the area.
But a dire night for Nigel Adkins' men was complete when Willy Caballero saved David Meyler's penalty.
And Willian was inches away from the hat-trick his display deserved when another long-range effort came back off the post two minutes from time.
Leicester joined Chelsea in the last eight as Riyad Mahrez provided the spark for the Foxes on his return to the starting line-up.
The Algerian's only appearance in Leicester's previous three outings came as a late substitute in a 5-1 drubbing at Manchester City last weekend following his self-imposed exile from training after Leicester rejected City's advances for the winger last month.
However, he showed why the runaway Premier League leaders were interested with the teasing cross for Jamie Vardy to head home the only goal in a 1-0 win over Sheffield United.