Kemar Roofe's second-half double ensured Oxford United conjured up the biggest upset of the FA Cup third round by beating Premier League strugglers Swansea City 3-2.
Oxford have lost just three times in League Two this season to sit third in the table and Swansea discovered why they have been so hard to beat at the Kassam Stadium on Sunday.
Jefferson Montero's cheeky finish to put the Welsh side in front in their first game since it was confirmed that Alan Curtis would remain in charge for the rest of the season, but Liam Sercombe levelled from the penalty spot just before half-time.
Midfielder Roofe then stole the show after the break, cutting in from the left before finding the far corner of the net with his right foot from just outside the penalty area and then rounding off a counter-attack to make it 3-1.
A Bafetimbi Gomis strike got Swansea back into the tie, but Michael Appleton's side held on for a famous win as Swansea's miserable season sunk to a new low.
Harry Kane rescued a 2-2 draw for Tottenham with a late penalty after Premier League rivals Leicester City looked set to go through at White Hart Lane.
Christian Eriksen gave the London club an early lead, but Marcin Wasilewski levelled in the first half and Shinji Okazaki put Claudio Ranieri's men in front just after the break.
England striker Kane came off the bench to thwart the club where he spent a loan spell in the 2012/13 season, slotting home his 14th goal of the campaign from the spot after Nathan Dyer had been penalised for handball to earn a replay.
A goal in each half from Diego Costa and Ruben Loftus-Cheek ensured Chelsea saw off League One side Scunthorpe United 2-0 at Stamford Bridge.
Guus Hiddink lifted the FA Cup during his previous spell as Chelsea interim manager in 2009 and the Dutchman will be eyeing a repeat in May after the Premier League champions made it five games without defeat since his appointment.
It was a bad day for the Welsh sides, as Shrewsbury belied their lowly position in League One by winning 1-0 at Championship outfit Cardiff City courtesy of an Andy Mangan header, while Yeovil Town drew 2-2 in an all-League Two tie at Carlisle United.