Callum Hudson-Odoi scored on what could be his final Chelsea appearance and Willian netted twice as the holders advanced with a 3-0 FA Cup fourth-round win over Sheffield Wednesday at Stamford Bridge.
Hudson-Odoi started despite reportedly submitting a transfer request in an effort to force through a move to Bayern Munich ahead of Thursday's transfer deadline and the 18-year-old winger netted Chelsea's second after 64 minutes.
Until that moment, an official, sitting 14 miles away in Stockley Park, had been the most influential person of the contest, despite the fact Gonzalo Higuain was making his Chelsea debut.
Wednesday had a penalty overturned by Video Assistant Referee Graham Scott after 22 minutes and Chelsea had a spot-kick awarded four minutes later, Willian converting from the spot, after referee Andre Marriner's decision had been confirmed by VAR.
Willian added a late third as the Blues advanced to the fifth round.
Higuain made his first appearance and Hudson-Odoi potentially his last as Chelsea made eight changes following last Thursday's win over Tottenham which saw them advance to the Carabao Cup final.
Wednesday's defence offered up a greater resistance than the England batting line-up their incoming boss Steve Bruce has witnessed in the Caribbean.
Bruce insisted on fulfilling his promise to go on a family holiday following the death of both his parents last year and watched England's 381-run first Test loss in Barbados ahead of taking up his role at Hillsborough from Friday.
Cricket's Decision Review System has largely been a success, but VAR has had its moments. On this occasion it was right, frustrating nearly 6,000 visiting fans.
When Joey Pelupessy surged through to try to meet Steven Fletcher's pass, Ethan Ampadu slid in and won the ball before being kicked by the Wednesday midfielder. Marriner's award of a penalty was swiftly overturned by VAR.
Play restarted with a dropped ball, as per the rules, which Wednesday did not contest. Soon they had conceded a spot-kick.
Blues academy graduate Sam Hutchinson trod on Cesar Azpilicueta. Marriner's decision was reviewed, but there was no doubt.
Willian appeared to offer the spot-kick to Higuain, who declined, before the Brazilian sent goalkeeper Keiren Westwood the wrong way for his 50th Chelsea goal.
The hosts celebrated in front of the Shed End, packed with visiting fans, some of whom took exception, with the launching of missiles.
Higuain, until that point, had lurked menacingly. He had one half-chance after a pass from Mateo Kovacic. He turned and shot, but the ball deflected wide.
The 31-year-old striker, who had the best goalscoring season of his career under Sarri at Napoli, netting 36 times in 35 Serie A games, dropped deeper and deeper as the first half progressed in search of the ball, while Hudson-Odoi was a peripheral figure.
Chelsea, as usual under Sarri, dominated possession, but little was created with the ball in the final third, while Wednesday's best chance was a mis-hit cross by Adam Reach which hit the outside of a post.
The Blues' lack of killer instinct has become a familiar frustration for the Italian, one he believes Higuain can solve.
He had half chances when a Willian cross was deflected away from him and heading an Ampadu cross just wide.
Chelsea scored their second when Andreas Christensen's long pass found Hudson-Odoi on the right. He checked inside, wrong-footing Morgan Fox, and struck a shot which deceived Westwood.
His second Chelsea goal could be his last.
Chelsea had a third when Willian played a one-two with Olivier Giroud, on for Higuain, and passed the ball in.
A Giroud overhead kick went wide and Willian shot off target late on, missing out on a hat-trick.