Match ends, MK Dons 1, Chelsea 5.
Milton Keynes Dons 1-5 Chelsea
A first-half Oscar hat-trick set Chelsea on their way to a thumping FA Cup fourth-round win at MK Dons.
The Blues went ahead early on when Diego Costa capitalised on Kyle McFadzean's mistake to set up Oscar but the hosts equalised through Darren Potter's deflected strike.
Oscar finished sublimely twice, before Eden Hazard scored his first Chelsea goal of the season from the spot after Potter fouled him.
Bertrand Traore slotted home his first Chelsea goal from Hazard's cross to wrap up proceedings.
Victory over a side 20th in the Championship leaves Chelsea boss Guus Hiddink, winner of the FA Cup with the Blues in 2009, still undefeated in eight games since replacing Jose Mourinho at Stamford Bridge.
Their reward for Sunday's FA Cup success was a home tie against Manchester City in the fifth round.
"It's already a final now. It's a huge game," Hiddink said.
Hazard ends drought
Hiddink chose to give Belgium international Hazard, who has recovered from a groin injury, his first start since 3 January, hoping last season's Premier League player of the year would end a run of 28 games without a goal.
Hazard linked well with left-back Baba Rahman throughout - causing Jordan Spence no end of problems - but it looked like that goalless streak would continue when Dons goalkeeper David Martin somehow kept him out when one-on-one in the first half.
However, in the second half, Hazard drew a foul in the box from Potter and calmly placed the ball the other side of Martin.
Asked why Hazard instead of Oscar took the penalty, Hiddink said: "They decided themselves because we have this hierarchy of the penalties. Oscar gave it to Eden as everyone knows he has not scored for a long time."
Hazard, 25, then chased down a long ball up field to lay the ball into the path of Traore to strike home before being replaced by Pedro shortly afterwards for a morale boosting performance.
Chelsea profligate despite win
Chelsea named a strong side, with only Ruben Loftus-Cheek not a Premier League regular, but the Blues were wasteful in front of goal against a side struggling in the Championship, having 15 efforts in the first half.
A tame Diego Costa effort was foiled by Martin early on and Oscar missed two decent opportunities before scoring his first - a tap in after Costa's persistence.
Martin, whose defence struggled to cope with the sheer pace of Chelsea's attacks, pulled off a fine save when Oscar played into an unmarked Diego Costa on the edge of the six yard box but his effort was tame.
After Potter's strike looped off Matic and over Courtois, Costa missed with the goal gaping from a ball into the middle.
But Oscar finally had his side in front again when Loftus-Cheek's past split the defence and the Brazilian finished with aplomb before making it 3-1 before the break with a strike from outside the box.
Dons lack forward thrust
Karl Robinson's side are the lowest-scorers in the Championship and were dealt a blow before kick off as Nicky Maynard was only fit enough for the bench.
With Dean Bowditch ploughing a very lonely furrow up front on his own, the hosts were restricted mostly to long shots, with on-loan Bolton winger Rob Hall seeing an effort tipped over the bar.
Substitute Daniel Powell jinked his way through the Premier League's side defence but his strike, saved by the feet of Courtois, was the closest the hosts came to a second.
"This was a free game for us but I'm disappointed as well, I thought we were poor," Robinson told BBC Sport.
"We almost caused our own problems at times in the game."
'Oscar fulfilled his obligations'
Chelsea boss Hiddink revelled in his side's victory and Oscar's hat-trick performance.
"We are delighted," said the Blues' interim manager. "The concentration against the big teams is always high but these games you have to be well prepared mentally. They got even but we reacted very well."
"Oscar is playing with a smile on his face and that's what I like with the players when they know their obligations and they do it."
The stats you need to know
- Oscar's the first player to score a first-half FA Cup hat-trick since Reuben Reid for Plymouth against Lincoln in November 2013.
- Potter scored his first goal since May 2015 and his first FA Cup goal since January 2013 against QPR.
- Hazard scored his first goal in 29 appearances for Chelsea this season (2,043 minutes without a goal this season).
- MK Dons conceded five goals in an FA Cup tie for the first time.
- Hiddink has won all five of his games in the FA Cup, seeing his team score 13 and concede three.
Chelsea have a Premier League trip to Watford on Wednesday, while MK Dons are in Championship action at Cardiff next Saturday.
- 12SpenceBooked at 80mins
- 16WalshBooked at 74mins
- 14CarruthersSubstituted forPowellat 82'minutes
- 31MurphySubstituted forWilliamsat 67'minutes
- 9BowditchSubstituted forMaynardat 76'minutes
- 26TerryBooked at 31mins
- 8OscarSubstituted forWillianat 64'minutes
- 10E HazardSubstituted forRodríguez Ledesmaat 64'minutes
- 19Diego CostaSubstituted forTraoreat 57'minutes
- 17Rodríguez Ledesma
- Jonathan Moss
- Shots on Target
Second Half ends, MK Dons 1, Chelsea 5.
Ruben Loftus-Cheek (Chelsea) wins a free kick in the defensive half.
Foul by Darren Potter (MK Dons).
Delay over. They are ready to continue.
Delay in match Willian (Chelsea) because of an injury.
Corner, MK Dons. Conceded by Bertrand Traore.
Attempt saved. Daniel Powell (MK Dons) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Darren Potter.
Foul by Baba Rahman (Chelsea).
Jonathan Williams (MK Dons) wins a free kick in the defensive half.
Attempt blocked. Pedro (Chelsea) right footed shot from the left side of the box is blocked. Assisted by Willian.
Substitution, MK Dons. Daniel Powell replaces Samir Carruthers.
Attempt missed. Jake Forster-Caskey (MK Dons) left footed shot from outside the box is too high. Assisted by Dean Lewington.
Jordan Spence (MK Dons) is shown the yellow card for a bad foul.
Baba Rahman (Chelsea) wins a free kick on the left wing.
Foul by Jordan Spence (MK Dons).
Attempt missed. Bertrand Traore (Chelsea) left footed shot from the centre of the box is close, but misses to the left. Assisted by Baba Rahman.
Foul by Cesc Fàbregas (Chelsea).
Samir Carruthers (MK Dons) wins a free kick in the defensive half.
Substitution, MK Dons. Nicky Maynard replaces Dean Bowditch.
Attempt blocked. Willian (Chelsea) right footed shot from outside the box is blocked.
Joe Walsh (MK Dons) is shown the yellow card for a bad foul.
Ruben Loftus-Cheek (Chelsea) wins a free kick in the attacking half.
Foul by Joe Walsh (MK Dons).
Attempt saved. Cesc Fàbregas (Chelsea) left footed shot from a difficult angle on the left is saved in the bottom left corner. Assisted by Pedro.
Corner, Chelsea. Conceded by Jordan Spence.
Offside, MK Dons. Samir Carruthers tries a through ball, but Robert Hall is caught offside.
Offside, Chelsea. Baba Rahman tries a through ball, but Bertrand Traore is caught offside.
Attempt blocked. Pedro (Chelsea) right footed shot from outside the box is blocked. Assisted by Baba Rahman.
Substitution, MK Dons. Jonathan Williams replaces Josh Murphy.
Substitution, Chelsea. Pedro replaces Eden Hazard.
Substitution, Chelsea. Willian replaces Oscar.
Goal! MK Dons 1, Chelsea 5. Bertrand Traore (Chelsea) left footed shot from the centre of the box to the bottom right corner. Assisted by Eden Hazard.
Corner, MK Dons. Conceded by Thibaut Courtois.
Attempt blocked. Robert Hall (MK Dons) left footed shot from outside the box is blocked. Assisted by Jordan Spence.
Foul by Oscar (Chelsea).
Dean Bowditch (MK Dons) wins a free kick in the defensive half.
Attempt blocked. Baba Rahman (Chelsea) left footed shot from outside the box is blocked. Assisted by Eden Hazard.
Substitution, Chelsea. Bertrand Traore replaces Diego Costa.
Attempt saved. Josh Murphy (MK Dons) right footed shot from outside the box is saved in the centre of the goal. Assisted by Jake Forster-Caskey.