As Chelsea romped to victory at Stamford Bridge, there were plenty of questions to be answered after the mid-week sacking of Jose Mourinho.

Guus Hiddink was named interim manager until the end of the season before kick-off, but fans still felt a lingering discontent.

And as Pedro, Branislav Ivanovic and Oscar struck to give the Blues a much-needed victory, we look at five things we learnt from the match.

Who the fans blame

Mourinho’s departure has left a sour taste in the mouth of fans, who felt indebted to the Portuguese manager. After all, he has proven to be symbolic of the Blues’ success.

And after the former Chelsea man argued his players betrayed him in Monday evening’s defeat to Leicester, fans took to booing Cesc Fabregas, Oscar and Diego Costa in the team announcement before kick off.

Show of support: A Chelsea fan holds a banner to support Jose Mourinho

Oscar is still brilliant

The Brazilian midfielder has suffered from poor form this season at the Blues, with a January move to Serie A and Juventus mooted.

But he was electric against Sunderland, with back-heels and a rabona cross just a couple of the wonderful moves he produced in helping the hosts to victory.

From the spot: Oscar converts his penalty

Hiddink will be eager to start

The Blues went into the weekend lingering in 16th in the Premier League, and the appointment of Guus Hiddink was announced just an hour before kick-off.

And the former Netherlands manager will be eager to start his second stint at Stamford Bridge, and the Blues players seemed equally eager to put their turbulent Mourinho time behind them with their strong showing against Sam Allardyce’s men.

Change of guard: Chelsea interim manager Guus Hiddink (L), Didier Drogba (R) of Montreal Impact and Chelsea owner Roman Abramovich

Defensive problems linger

Chelsea have lost nine of their opening 16 Premier League games this season and it is hardly surprising that a big cause of this has been their lack of defensive security.

The Blues looked strong in attack against Sunderland, and mostly nullified the opposition’s midfield but the Black Cats still had chances in attack.

Borini scored, and both Duncan Watmore and Jermain Defoe caused them problems in spells throughout the game. Lessons must be learnt if they are to improve.

Battle: Mikel battles for the ball

Fans are restless

Undoubtedly the second sacking of Mourinho has left fans feeling bereft as they booed the prime suspects behind his sacking before kick-off.

The Blues will rise to 14th in the Premier League after beating Sunderland, but they still have plenty of work to do before fans can get back on side - particularly those who were deemed to play a fundamental role in the sacking of Mourinho.