Tottenham manager Jose Mourinho defended Eric Dier after the England international stormed into the stands following his side's FA Cup exit to Norwich on Wednesday.
Dier climbed over rows of seats to confront a fan, who had allegedly been involved in an altercation with the player's brother.
The incident rounded off a terrible night for Tottenham, who saw another chance of silverware slip away 3-2 on penalties after a 1-1 draw against the side bottom of the Premier League.
"When someone insults you and your family is there and your family gets involved with somebody who is insulting you, in this case a younger brother, I think Eric did what we professionals cannot do but, I repeat, probably everyone of us would do," said Mourinho.
"I am with the player and I understand the player."
Dier scored his penalty in the shootout, but Erik Lamela, Troy Parrott and Gedson Fernandes missed from the spot to condemn Spurs to a fourth straight defeat in all competitions.
On the prospect of the club taking disciplinary action against Dier, Mourinho added: "If the club does that I will not agree, but he did wrong."
Jan Vertonghen headed Tottenham into an early lead, but Mourinho's decision to hand 36-year-old goalkeeper Michel Vorm his first appearance of the season backfired.
The Dutchman spilt a long-range effort from Kenny McLean and Josip Drmic bundled home the rebound to level 12 minutes from time.
Both sides then tired badly in extra-time, but neither could find a winner and Mourinho again blamed his stretched resources without the injured Harry Kane and Son Heung-min to injury for defeat.
"Some of my players were really in trouble and they made an incredible effort to try," said Mourinho.
"I don't have one single negative feeling towards my players. I can cope with negative moments in football, but I feel really sorry for my players."
Norwich will host Derby or Manchester United in their first quarter-final since 1992.
- City win for 'crazy' Guardiola -
Manchester City will travel to Newcastle in the last eight after winning a 20th consecutive domestic cup tie 1-0 win at Sheffield Wednesday thanks to Sergio Aguero's winner.
Wednesday goalkeeper Joe Wildsmith failed to get a strong enough hand to the Argentine's low strike eight minutes into the second half.
A solitary goal was scant reward for the dominance of Pep Guardiola's men, but they maintained hopes of a cup treble after lifting a third consecutive League Cup on Sunday and beating Real Madrid 2-1 in the first leg of their Champions League last-16 tie.
"He is a good manager and crazy," said Aguero of Guardiola's relentless demand to keep winning.
Leicester also booked their place in the last eight with a much-needed 1-0 win over Birmingham thanks to Ricardo Pereira's late header.
The Foxes have won just one of their last seven Premier League games to stall their charge towards the Champions League next season.
Brendan Rodgers' men were again without Jamie Vardy through injury and needed right-back Ricardo to get the only goal when he headed home Marc Albrighton's cross eight minutes from time.
"I thought it was just a matter of time," said Rodgers, whose side will host Chelsea in the quarter-finals.
"In the second half we dominated -- lots of quick combos and the goal was coming. It was an excellent display."
Sheffield United will host Arsenal in the other quarter-final tie.