Kemar Roofe
Roofe's double ensured he was the toast of Oxford as they shocked the Premier League side.Getty Images

Oxford United staged the standout giant-killing of the FA Cup third round after dumping out Premier League Swansea City in a thrilling game at the Kassam Stadium. Kumar Roffe scored twice in the second half to upset Alan Curtis' side who had led through Jefferson Montero's first goal of the season.

Liam Sercombe hammered home a penalty on the stroke of half-time after Alex MacDonald was fouled by Kyle Barkley. Roofers curled effort from 20 yards put the U's ahead four minutes after the interval before the ex-West Bromwich Albion youngster finished off a fine breakaway move before the hour to double the advantage.

Bafetimbi Gomis pulled one back with a quarter of the game remaining but Swansea were unable to complete the comeback. Victory for Michael Appleton's Oxford saw them become the first fourth-tier side to knock-out top flight opposition since 2012.

At White Hart Lane, Tottenham Hotspur had referee Robert Madley to thank after a controversial late penalty allowed Harry Kane to secure a replay against Leicester City. Marcin Wesolowski and Shinji Okazaki's goals, following Christian Eriksen's opener had Leicester on course to go through but Madley adjudged Lloyd Dyer to have handled in the area; allowing Kane to level with his 50th Spurs goal in the 89th minute.

Harry Kane
Kane netted his 50th Tottenham goal to set up a replay.Getty Images

"Of course [the result feels like a defeat]," Foxes boss Claudio Ranieri said. "There are very few minutes left at the end of the match and there was this penalty. I didn't see the penalty because there were players in front of me. I don't know if they touch but the more important thing is the referee gave the penalty, it is a penalty.

Shrewsbury Town caused a surprise by knocking out 2008 finalists Cardiff City in south Wales. Former Wrexham striker Andy Mangan headed home the only goal from Scott Vernon's deep cross as the League One strugglers reached the fourth round for the first time since 2003. Sammy Ameobi hit the foot of the post and Federico Macheda was denied by Mark Halstead's save to leave Russell Slade's side frustrated in front of a crowd of just 4,782 at the Cardiff City Stadium - the second lowest attendance in the ground's history.

Elsewhere, Premier League champions Chelsea outlasted League One side Scunthorpe United to ease into the fourth round. Diego Costa converted from Branislav Ivanovic's cross prior to substitute Ruben Loftus-Cheek netted his first Blues goal from Cesar Azpilicueta's pull back.

"It was not an easy game but I think we started well," interim boss Guus Hiddink said. "We got an early goal but we were a little bit cocky and in finishing off the game an going 2-0 up in the first 20 minutes. We knew we were very dangerous particularly on their set pieces especially corners so the equaliser is always in the air."

Carlisle United continued life away from they flood-damaged Brunton Park home with a 2-2 draw with Yeovil Town. The Cumbria club twice took the lead through Danny Grainger and Mark Ellis - in a tie played at Blackpool's Bloomfield Road - but were pegged back first through Francois Zoko's header and then Shaun Jeffers' smart finish in the 90th minute.

FA Cup third round results:

Oxford United 3-2 Swansea City, Chelsea 2-0 Scunthorpe United, Carlisle United 2-2 Yeovil Town, Tottenham Hotspur 2-2 Leicester City, Cardiff City 0-1 Shrewsbury.