Tottenham manager Ange Postecoglou said he suffered "cold sweats" worrying that his integrity could be questioned over his side's midweek match against Manchester City, which the champions won 2-0.
The former Australia boss admitted he was wrong to scoff at suggestions that Spurs fans would want their own side to lose in order to deny north London rivals Arsenal the Premier League title.
City's victory took them two points clear of the Gunners at the top of the table heading into Sunday's final day of the season.
Despite the subdued atmosphere on Tuesday, Spurs made Pep Guardiola's men work hard and could easily have snatched a point had Stefan Ortega not saved from Son Heung-min late on.
"That's probably the worst experience I've had as a football manager in a game," Postecoglou said at his pre-match press conference on Friday.
"Once I realised I'd got it wrong in terms of what the atmosphere was going to be like and what people felt, I got a real anxiety within me. What happens if Man City, the best team in the world, who were disposing of teams quite easily in the lead-up, what if we play as well as we can but they beat us 5-0?
"I got cold sweats thinking about people questioning my integrity and the people I work with."
A furious Postecoglou was involved in an angry exchange with a supporter behind the Tottenham bench during the match and said after the game the foundations he had built in his first season were "fragile".
Spurs just need to avoid defeat away to relegated Sheffield United on Sunday to secure a fifth-placed finish and Europa League football.
But Postecoglou believes much more work needs to be done to instil a winning mentality at a club that has not won a trophy since 2008.
"Supporters are there to back their club and do their bit," he said. "They've certainly done their bit for us this year. The amount of games we've won late at the stadium has been extraordinary and the supporters have played a big part in that.
"The last game, I don't understand. I sat here the day before and mocked the whole thing. I really didn't believe that was the case. But if that's how people feel? I'm not a Spurs supporter. They are. They're the custodians, not me.
"All I can say is to offer my opinion on what you need to be successful. For me, you can't be successful if your motivations change depending on the contest. You've got to want to win all the time.
"It wasn't just Spurs supporters. Everyone I heard said they understand how they feel. Well I don't understand. I just can't think of anything worse than not going all in on victory every time you're out there."
