LONDON -- Antonio Conte insisted that the video assistant refereeing (VAR) system must be improved after watching his nine-man Chelsea team narrowly overcome Norwich City in a dramatic FA Cup third round replay at Stamford Bridge.
Michy Batshuayi put the Blues on course for the fourth round on 55 minutes when he turned in Kenedy's low cross, but Jamal Lewis met Tom Klose's cross with a glancing header in the 94th minute to send the tie to extra-time.
The VAR system, being trialled in both domestic cup competitions this season, then became the subject of controversy when referee Graham Scott judged Willian to have dived in an attempt to win a penalty and showed him a yellow card.
Klose admitted after the match that he felt he caught the Brazilian, but video official Mike Jones did not see a clear and obvious error in Scott's decision and so the incident was not subject to a full review.
Conte, who watched a video replay of the collision, called it a "big, big mistake" and added: "I think that we need to improve if we want to use this new system.
"The referee took quickly a decision to book Willian. That means you don't have doubt. If we want to improve we have to wait to check with the person who is watching the game and then, if this person is sure 100 percent that it is simulation, go and book Willian. Instead, I think the person watching the game at least must have a doubt. There is a kick to Willian and he should call the referee and tell him.
"If we want to use a new system, I can't accept a big mistake. In this case, the Willian penalty was a big, big mistake. Not from the referee on the pitch, but from the person watching the game. If you're watching the game and don't see this situation ... I hope the VAR wasn't a referee because if you see that watching on television and don't think that's a penalty ... He has to improve and must improve."
Chelsea were reduced to nine men in extra-time after Pedro, earlier booked for diving, caught Wes Hoolahan late and Alvaro Morata received a second yellow in a matter of seconds for dissent as he protested being penalised for diving in the box.
Yet despite missing two players who may well have taken penalties, Chelsea won the shootout 5-3 with Willian, David Luiz, Cesar Azpilicueta, N'Golo Kante and Eden Hazard all scoring while Willy Caballero saved from Norwich striker Nelson Oliveira.
Asked why his players had dived, Conte replied: "I don't know, but I don't want an advantage. About Pedro, if there is a dive, it's right to take a yellow card. It's the same for Morata."
Conte admitted he was disappointed in Morata's indiscipline, but insisted that he was broadly pleased by his team's performance.
"I think our performance was positive," he continued. "Despite making many changes, we scored a goal and made many chances to score a second. Instead they drew with 10 seconds to go."
Chelsea face Newcastle United at home in the fourth round on Jan. 28 but Conte cannot look beyond Saturday's trip to face Brighton in the Premier League, where he must factor in fatigue from his team's FA Cup exertions without the suspended Morata and Pedro.
"We have to try to recover very well, for sure," he admitted. "I hope we don't pay. My decision was very clear: To try to go to the next round and give a bit of rest for the other players. But it won't be easy against Brighton. It'll be important to rest and recover. Also two red cards, so Pedro and Morata cannot play."