Conte won the Premier League and FA Cup at Stamford Bridge but was sacked by the Blues in the summer following a turbulent season.
Former Napoli boss Sarri was named as his replacement and the Italian has enjoyed an impressive start to his managerial career in England.
Chelsea are currently third in the Premier League and top of their Europa League group, and Willian has heaped praise on the new Blues boss.
‘It’s been a very good start, we’ve played good football and it’s all credit to Sarri,’ Willian told Sky Sports. ‘The way he works, it is all about playing good football and he has given us more opportunities to show our quality more.
‘I am not here to criticise other managers or how they worked because every manager has a different philosophy. ‘Now everyone can see Chelsea is a good team; he [Sarri] is a very positive guy – very intelligent, a very good manager who talks all the time with us.
‘Sometimes he has a lot of fun and jokes sometimes which is good to keep the atmosphere high.
’ Chelsea appeared to be heading for their first Premier League defeat of the season last weekend after Manchester United overturned a 1-0 deficit to lead at Stamford Bridge.
But England international Ross Barkley scored an injury-time equaliser to maintain Chelsea’s unbeaten start to the new campaign.
‘We have no one to fear in the Premier League this season, we have a team who will fight until the end and I am sure we are going to do that,’ Willian added. Chelsea travel to Turf Moor to face Sean Dyche’s Burnley on Sunday.