Kyle Walker-Peters says his Champions League slip that led to Ousmane Dembele's opening goal in the Nou Camp will be as big a mental test as he faces.
The young defender's dream Champions League debut in Tottenham's decisive group game against Barcelona quickly turned into a nightmare as his mistake led to Dembele's opener in the first 10 minutes.
The 21-year-old then picked up a booking before making way in the second half as Spurs chased the goal that ultimately sent them through to a last-16 tie with Borussia Dortmund.
"I learnt a lot about myself," he said. "Two seconds after making the mistake, I was thinking, 'You know, make sure you don't die on the pitch!'"
The youngster had signed a five-year contract extension just 24-hours before and is optimistic about his Tottenham future.
"I think I went on to actually play quite well," he added. "I think I've got a good amount of mental toughness, to be able to do that. But again, it's all a learning curve for me.
"Especially coming in the Champions League, in a stadium like that against such a good team. To be able to look past that... also with the help of my team-mates straight away."
Walker-Peters believes being around experienced first-team players has helped his development.
"Danny Rose came straight over to me and said, 'Keep going'. Harry Kane as well, he said a few things to me. As we went to take the kick-off he just said, 'Keep going. There's plenty of time'.
"That gave me confidence and that's why I went on to play quite well.
"It's always going to happen once in your career. Now it's happened I feel like I know how to deal with it. If it ever happens again - touch wood it doesn't - I'll know how to respond."
Tottenham boss Mauricio Pochettino has confirmed Walker-Peters is in his plans for the future and with fellow right-backs Kieran Trippier and Serge Aurier struggling with injuries, he could become a regular.
"If I get the opportunity, I'd be really buzzing. All I can do is appreciate that (Pochettino's comments).
"That starts on the training pitch by showing him every day that I'm willing to keep working, keep improving. Those words from the gaffer always help, especially as a young player hearing your manager has faith in you."