Tottenham Hotspur 4-3 Wycombe Wanderers
Son Heung-min's stoppage-time winner saw Tottenham recover from being a goal down with a minute to go against League Two Wycombe in the FA Cup fourth round.
Paul Hayes, who had earlier headed against the bar, shocked the Premier League side with a sweetly struck left-footed volley to put Wycombe ahead.
The captain grabbed his second from the spot to double the visitors' lead.
But Son's deflected effort on the hour and a Vincent Janssen penalty four minutes later pulled Spurs level.
Substitute Garry Thompson headed in Myles Weston's cross with seven minutes to go to put Gareth Ainsworth's side back in front.
But a composed 89th-minute finish from Dele Alli pulled Spurs level again, before Son scrambled in a late winner.
- BBC One is showing two live FA Cup ties on Sunday. Millwall host Watford at 12:00 GMT, followed at 16:00 GMT by holders Manchester United against Wigan.
Chairboys' experience shows
Wycombe boss Ainsworth said there was "no pressure" on his side when arriving at White Hart Lane, and the side 70 places below Tottenham in the league pyramid will take heart from a performance that saw their 16-match unbeaten run in all competitions come to an end.
That run has taken the Chairboys from a relegation battle into sixth place in the fourth tier and they had already surpassed expectations in the FA Cup by reaching the fourth round for only the second time in the club's history.
Roy Essandoh was the hero with a late winner when Wycombe shocked Leicester City to reach the semi-finals in 2001, while it was 33-year-old Hayes who looked to have written the headlines this time around - his stunning volley setting the League Two side on their way.
The Wycombe skipper was complemented by veteran forward Adebayo Akinfenwa, whose physical presence caused problems for a young Spurs defence from the first minute when he nodded across goal for his strike partner to head against the bar.
The front two made way for Weston and Thompson midway through the second half, and it was the substitutes who combined to put Wycombe within a whisker of a memorable FA Cup upset.
Spurs lacking strength in depth?
Tottenham boss Mauricio Pochettino was always likely to rotate a squad hoping to sustain a title challenge - one he has said does not need strengthening in the final days of the January transfer window.
The Argentine made nine changes to the side that fought back to draw at Manchester City last week, but Tottenham's second string largely failed to impress and did little to suggest Spurs have the strength in depth to go the distance in the Premier League.
Teenager Cameron Carter-Vickers looked composed on the ball, but struggled with the physical threat of Akinfenwa, while there was plenty of promise but little end product from attacking trio Josh Onomah, Georges-Kevin Nkoudou and Moussa Sissoko.
The hosts dominated, especially in the second half, but it took the introduction of striker Janssen at half-time and first-teamers Alli and Mousa Dembele on the hour mark for Spurs to eventually creep past a resilient Wycombe.
They did show character, however, and that comeback came despite going down to 10-men when full-back Kieran Trippier limped off after Pochettino had made all three changes.
Man of the match - Paul Hayes (Wycombe)
Manager reaction - 'The beauty of the FA Cup'
Tottenham boss Mauricio Pochettino: "That is the beauty of the FA Cup. It was an unbelievable game. Full credit to Wycombe, they played very well first half.
"It is completely different to Spain and France. Here it is special - the team, the people is mad to try and lift the trophy. It is completely different to when you play Premier League or EFL Cup."
On whether Spurs are looking to win the competition: "Of course, but you have to give players opportunities to play in the squad and assess them."
Wycombe manager Gareth Ainsworth: "That's the rollercoaster that is football management - those last 10 minutes, I don't know where to start.
"The lads have done me and the town so proud. What we have done today puts a marker down of how far we've come. I hope everyone respects we gave it a go."
Stats - Hayes rises to top-flight occasion
- Son Heung-Min has scored in each of his last three starts for Spurs at White Hart Lane (four goals).
- Paul Hayes scored twice in an FA Cup game for the first time since December 2005, when he was playing for Barnsley against Bradford.
- Hayes has scored in three of his last four FA Cup appearances against Premier League opposition - he scored for Scunthorpe against Chelsea in 2005 and Manchester City in 2010.
Tottenham travel to Sunderland in the Premier League on Tuesday (19:45 GMT), before hosting Middlesbrough next Saturday (17:30).
Wycombe return to League Two action at Exeter City on Tuesday (19:45), before welcoming play-offs rivals Portsmouth on Saturday.