BBC News Online in Lisbon
England fans in Lisbon have been speaking of their shock at the death of a Briton during an alleged robbery.
Things are back to normal in the streets around Rossio Square
Stephen John Smith, 28, was stabbed in the city's central Rossio Square, where many fans had been celebrating the 4-2 win over Croatia.
A man, thought to be Ukrainian, was arrested following the attack, at 0400 BST.
The atmosphere after the game had been a peaceful, friendly one, with England and Croatian fans out together, and no signs of any trouble.
"This is terrible, it puts a real dampener on things," said Louis Calders from Mansfield.
"When we left the square it was very jovial, with 300 fans singing and conga-ing."
On Tuesday morning England supporters returning to the square for breakfast had only just learned of Mr Smith's death.
Emily Orton and Russell Anderson were shocked by the stabbing
"I'm shocked by this, it's really quite scary," said Emily Orton, 27, from Exeter.
"Everyone was just having such a good time, and now this has happened."
Her friend, Russell Anderson, 24, from Chelmsford in Essex, said: "It was actually quite quiet after the game, there was a really nice chilled atmosphere."
Chris Torkington, from Cumbria, agreed: "It's sadly ironic that this has happened because there was no trouble at all, just a great atmosphere."
Many fans said that despite their shock, they were relieved the death was not hooligan-related.
"There have been enough problems on the Algarve and we don't need things to get more dangerous following something like this," said Colin Danneau, from Croydon.
Others were anxious that people in England could get the impression that the death was somehow related to Euro 2004, or that Portugal was unsafe.
"Personally I think it's something that happens in big cities everywhere. It's really sad that someone's not going home to their family," said one.
Large numbers of England supporters are not staying in Lisbon and travelled back to their hotels on the Algarve coast after the game.
On Tuesday there were relatively few replica shirts to be seen, with those still in the capital planning to take in Lisbon's sights.
In Rossio Square all was back to normal, with the exception of a fountain draped with soaked England flags and filled with washing up liquid bubbles.
Supporters are now looking forward to what they hope will be a peaceful quarter-final against their hosts on Thursday.