Tottenham Hotspur manager Mauricio Pochettino has revealed that striker Vincent Janssen required a private “wake-up call” in his office earlier this season, but that he is happy with the way he has bounced back since.

Janssen scored his first goal from open play for the club in the 6-0 FA Cup win against Millwall last weekend, with Spurs fans hoping he can adequately fill-in for Harry Kane over the next few weeks, after the England international suffered ankle ligament damage in the same match.

The goal was just Janssen’s fifth in 25 appearances for Tottenham this season, with his preceding four goals all coming from the penalty spot. And the Dutch striker was so short of confidence during that spell that Pochettino felt it necessary to invite the player into his office in an attempt to boost his confidence.

“So far from the beginning of the season some players need a wake-up call in private, in my office,” said Pochettino.

“It is true that in the earlier period of the season his form was down and he needed a wake-up call to be reminded that the possibility of him playing could arrive.

“Now he is okay, he is motivated and confident. He is also feeling a little bit of relief after his first goal from open play and that is important. I am happy with the way that he has trained this week, too.”

Pochettino is pleased with the commitment shown by Janssen (Tottenham Hotspur FC via Getty)

There was much excitement at Tottenham when the club signed Janssen from AZ Alkmaar ahead of the new season, for £17m. The forward, who was awarded the 2016 Johan Cruyff Trophy for the best young Dutch player, had enjoyed a spectacular breakthrough season in the Eredivisie, scoring 27 goals in 34 league games.

But the 22-year-old has found adjusting to English football tough, despite proving a popular figure in the Tottenham dressing room. When he scored against Millwall, he was mobbed by all of his team-mates and given a warm reception by the White Hart Lane crowd.

Janssen has found opportunities hard to come-by, largely restricted to small cameos at the end of matches because of Harry Kane’s good form, and Pochettino appreciates that a lack of starts has made Janssen’s season even more difficult.

Tottenham 6 Millwall 0 player ratings Show all 22 1 /22 Tottenham 6 Millwall 0 player ratings Tottenham 6 Millwall 0 player ratings Michel Vorm – 5 out of 10 It was a quiet day at the office for the keeper due to very few attempts from the Millwall forwards. Getty Images Tottenham 6 Millwall 0 player ratings Eric Dier – 6 out of 10 Had a relatively straight forward day at the back, with few very Millwall moves causing him an issue. Getty Images Tottenham 6 Millwall 0 player ratings Toby Alderweireld – 6 out of 10 A disciplined display from the central defender. Did his job and held his shape at the back. Getty Images Tottenham 6 Millwall 0 player ratings Jan Vertonghen – 6 out of 10 Defended bravely and began moves from the back. Read the game well. Getty Images Tottenham 6 Millwall 0 player ratings Kieran Trippier – 7 out of 10 His assist for Son’s goal was sublime, as were the rest of his deliveries into the danger zones throughout. Getty Images Tottenham 6 Millwall 0 player ratings Victor Wanyama – 6 out of 10 Battled throughout and was a key element to Tottenham’s moves going forward. Getty Images Tottenham 6 Millwall 0 player ratings Harry Winks – 7 out of 10 Oozes confidence for a young lad and it was good to see taking shots on goal. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Ben Davies – 7 out of 10 Was charging up and down the wings, which provided Spurs with the width that they required. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Son Heung-min – 9 out of 10 The hat-trick hero was on fire today. His movement, work rate and finishing were all spot on. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Dele Alli – 7 out of 10 His goal marked his 16th of the season. His positioning was spot on today and he was always making space going forward. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Harry Kane – N/A Went off in the early stages of the game after losing his balance and appearing to injure his ankle. AFP/Getty Tottenham 6 Millwall 0 player ratings Tom King – 3 out of 10 Made a handful of important saves, but it’s never a good day when you concede six. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Shaun Cummings – 4 out of 10 Defended very narrowly, which allowed Spurs to cause damage in the wide areas. AFP/Getty Images Tottenham 6 Millwall 0 player ratings Byron Webster – 5 out of 10 Struggled to cope with Tottenham's pace going forward. CameraSport via Getty Images Tottenham 6 Millwall 0 player ratings Jake Cooper – 5 out of 10 Heung min-son made his life very difficult. AFP/Getty Images Tottenham 6 Millwall 0 player ratings Tony Craig – 5 out of 10 Defended bravely, but simply failed to contain the Spurs strikers. Getty Images Tottenham 6 Millwall 0 player ratings Jed Wallace – 6 out of 10 He tracked back and worked hard defensively, but failed to show any ability going forward. Getty Images Tottenham 6 Millwall 0 player ratings Ben Thompson – 5 out of 10 Lost the battle in the midfield and this allowed the opponents to dominate the play. Getty Images Tottenham 6 Millwall 0 player ratings Shaun Williams – 6 out of 10 His deliveries up the field were impressive, but they lacked the final product. Tottenham Hotspur FC via Getty I Tottenham 6 Millwall 0 player ratings Aiden O’Brien – 5 out of 10 Was forced to drop deep due to the quality of the Spurs defence. He was marked out of the game. AFP/Getty Images Tottenham 6 Millwall 0 player ratings Lee Gregory – 6 out of 10 His work rate was faultless, but he did not have enough time on the ball to actually make an impact. Getty Images Tottenham 6 Millwall 0 player ratings Steve Morison – 6 out of 10 Looked the most dangerous prospect for Millwall going forward. Getty Images

“It is complicated for the offensive players at the big teams, who are behind Harry Kane, Diego Costa, Alexis Sanchez or Zlatan Ibrahimović,” Pochettino said.

“But [Janssen] is young and has just arrived from Holland. I am happy with him and all the players but I understand that they are not happy with all situations.”

Tottenham will be hopeful that Kane’s injury does not derail their ambitions of a second successive top-four finish.

The club confirmed earlier in the week that he had suffered ankle ligament damage, although in a statement Spurs said the injury “is not considered to be as severe” as the one he suffered against Sunderland earlier in the season.

Kane injured his ankle ligaments against Millwall (Getty)

The club are however likely to be without their leading goal-scorer for a significant portion of the run-in, although Pochettino is confident Spurs can improve on their dismal league finish last year, when they took two points from their last four games and lost 5-1 to relegated Newcastle on the final day of the season.

“I am very confident like I was last season and what happened in the last three weeks was a big surprise for us,” said Pochettino. “But I hope that will not happen again for us. I hope that will not happen again the last three weeks like we finished.