On 5 April 2011, while Spurs were being torn apart at the Bernabeu, the 18-year-old was sat on the Leyton Orient bench, patiently waiting for his chance to come on in a League One game against Plymouth.
When Tottenham made their next trip in the same competition, the maturing Kane was being linked with a £200m-plus move to the 12-time European champions.
On 17 October 2017, the 24-year-old arrived in the Spanish capital as Tottenham and England’s talisman – splashed across the front of Madrid’s sports papers, the opponent to fear.
“His rise has been one of the biggest shocks of my footballing career,” Jermaine Jenas, his former Spurs team-mate, said.
As Real Madrid prepare to face Spurs at Wembley on Wednesday, BBC Sport analyses whether Kane has the talent, mental strength and marketability to become a Galactico.
Is he ‘a Real Madrid player’?
During his first spell as Real president between 2000 and 2006, Florentino Perez’s pursuit of the world’s most talented players and his extravagant spending to sign them coined a new term: Galacticos.
Portugal attacker Luis Figo and France midfielder Zinedine Zidane were the first of this new breed to arrive at the Bernabeu for world record fees, with Brazil striker Ronaldo, England captain David Beckham and striker Michael Owen also making the move over the next few seasons.
Perez left in 2006 amid criticism the club had become too focused on building its brand to the detriment of winning trophies, but returned in 2009 to complete the signing of Cristiano Ronaldo and then add Wales forward Gareth Bale four years later.
Kane, 24, is the same age as Ronaldo, Owen and Bale at the time of their respective transfers from the Premier League to Real Madrid, but does not have the same level of experience – at club, European or international level – as either of this trio.
Neither has he become a global star after illuminating a World Cup, European Championship or Champions League tournament.
Both Owen and Ronaldo had already won a Ballon d’Or – the prize awarded to the world’s best player of the year – and had won several domestic honours with their respective clubs.
“In Spain, we don’t consider him in the top 10 world-class players because he has only been playing a couple of years and is only playing at Tottenham, who are not in the Champions League semi-finals or final,” Juan Castro, a football journalist at Madrid-based sports newspaper Marca, said.
“Maybe in the Premier League he is an enormous player but if you go into a Spanish bar then not everyone knows him. He is not a big star.
“He has to prove it in a Champions League or a World Cup, like Luis Suarez, to demonstrate he is a master.”
However, Kane’s goalscoring record in the Premier League compares favourably to Ronaldo, Owen and Bale – although only Owen was already considered a striker when he moved, with Ronaldo and Bale used more out wide.
While Kane has not scored as many goals as Owen did, he has netted at a quicker rate than the former Liverpool striker.
The leap to the Bernabeu
Playing for a big club is one thing. Playing for Real Madrid is another.
The ability to maintain composure in the opposition penalty area is what separates the greatest strikers from the rest. Even more so when 80,000 Madridistas are losing their cool around you.
Real Madrid legend Emilio Butragueno, who scored 171 goals in a 12-year spell at the Bernabeu, became known as El Buitre (The Vulture) because of his clinical finishing.
What was the key to the former Spain striker’s success? “I left my mind blank for my body to act,” he once said.
Kane’s finishing ability has led to him being described as a “killer” striker by Spurs boss Mauricio Pochettino and former Real president Ramon Calderon believes the England international has the composure to succeed at the Bernabeu.
“You need to be calm in the penalty area otherwise you will be in trouble. You need to be cold to be a Real Madrid striker and I think he is. That’s one of his main qualities,” he said.
“But it is true that playing in the Bernabeu is difficult – sometimes even for players who have played for big clubs in different countries.
“It is different for some players when the fans boo – that doesn’t happen at Manchester United or Liverpool or other teams.
“But maybe that is why we have built a legend and won so many trophies because of the demands from our fans – players know they have to perform.”
Is he worth more than £200m?
Brazil forward Neymar became the first footballer to command a £200m transfer fee when he joined Paris St-Germain from Barcelona last summer and current Real president Perez believes Spurs would demand around £223m (€250m) for their prize asset.
“Kane is certainly worth around £200m because you would benchmark him against other strikers of his calibre,” said Kieran Maguire, a sport finance expert at the University of Liverpool.
“It’s a bit like when you are trying to work out how much a house is worth. You look at other houses down the street and if they are similar and going for ‘X’ then yours goes for ‘X’.
“Kane is at a prime age, there is still room for improvement and Real could sign him on a five or six-year contract, spreading the cost over that period.
“For a club of their financial strength it would not be a issue.”
Perez, having completed record deals for Figo, Zidane, Ronaldo and Bale over his two spells as president, has never been scared to splash the cash.
But for the 70-year-old construction magnate, a shrewd businessman with a net worth of $2.1bn, a big-money signing’s playing ability has to be equalled by one thing: their commercial value.
Ronaldo, 32, is the world’s highest-paid athlete, according to Forbes, raking in $35m of his $93m earnings last year through endorsements.
Real Madrid, with the Portugal forward as their poster boy, also brought in $216m through sponsorship deals – a revenue only bettered by Barcelona.
“Ronaldo is in a commercial league of his own and there will be a vacuum at Real Madrid when he hangs up his boots, whenever that might be,” Maguire said.
“Kane is quite dull – in a good way, he just gets on with his games, scores goals and has a squeaky clean image – and is not glamorous in the same way as Cristiano is. Very few players are.
“But if Kane scores lots of goals then that will attract sponsors.
“In the main they are trying to attract the 15-34 male group who don’t tend to watch a lot of television but do have disposable income.
“They are not bothered by the looks of the footballer, they want to be associated with a good footballer and a good guy – Kane falls into that bracket.”