The Portuguese tactician also revealed that he apologised to Eric Dier for taking him off early in the first half itself.

When the scoreline read a 2-0 deficit to Olympiakos after just 19 minutes, few people expected Jose to pull his side together and inspire a comeback in his first game at the Tottenham stadium. But Mourinho acted quickly as he took off Eric Dier in just the 29th minute of the game to put on the more attack-minded and creative Christian Eriksen instead. Shortly after, Dele Alli made the most of a horrendous error by Yassine Meriah to give the Spurs a bleak hope going into the half-time.

However, Tottenham Hotspur emerged out of the tunnel after half-time as a different side and scored three more in the second half to register a brilliant 4-2 comeback and book their place in the knockout stages. Jose Mourinho revealed that at half-time he told the players to control their emotions and believe in themselves that they can win the game.

“It was hard, they are a good team,” Mourinho said. “Very well organised and they attacked our self-esteem and self-confidence.

“I did not expect our boys to feel this pressure at home and they have not had the best results in the last few months. It was a tough time, more than the changes or the tactical talk. I told them to keep calm, keep confident and believe in ourselves.”

Harry Kane restored parity just minutes after half-time as he finished off a Lucas Moura cross with delight. Serge Aurier then put the side ahead and he was aided in this by the effort of a ball-boy who helped a quick throw-in that caught Olympiakos completely off-guard.

“I love intelligent ball boys like I was. I was a brilliant ball boy as a kid,” Mourinho told BT Sport. “And this kid today was brilliant. He reads the game, understands the game and made an important assist.

“He’s not there just to look to the stands, lights or scarves. He’s living the game and playing it very well.”

Mourinho sought out the ball-boy after the goal was scored and hugged and thanked him for his alertness.

Ball-Boy Assist: This is how it happened

Kane then headed in a sumptuous Eriksen free-kick to wrap things up and with this goal, he went past the great Alessandro Del Piero as the player needing the fewest games to score 20 Champions League goals.

Del Piero needed 26 to get to this figure whilst the Englishman managed it in just 24 games. “Not a bad player to beat,” said Kane afterwards. “It was about qualifying, no matter how we did it but we had to win and we did that.”

Jose also apologised to Dier after the game. “The most difficult moment of the game for me was not when Olympiakos scored their first or second goal. It was when I made the change in the first half,” he said.

“I hurt the player but hurt myself. He’s a very intelligent boy who has a good understanding of what a team is. It wasn’t about his performance, it was about what the team needed.

“I felt one midfield player was enough. We needed a second creative player who could play with Alli in an open triangle and not a closed triangle with Dier and Harry Winks. I apologised to him, although he knows I did it for the team. Christian gave us what we needed.”