English football supporters are under the spotlight following a second night of violence involving police in Europe.
Tottenham fans clashed with police in Spain during their Uefa Cup tie at Sevilla just 24 hours after Manchester United's Champions League match at Roma had been marred by similar problems.
European football's governing body Uefa are to investigate both incidences of crowd disorder.
Reports in Spain suggested eight people had been taken to hospital with minor injuries, seven of whom were thought to be Tottenham fans, one with a suspected broken wrist. One policeman was also reportedly injured.
Riot police had been deployed in the area housing around 4,000 Spurs fans less than half an hour into the game.
The problems appeared to die down but were resurfaced after Alexander Kerzhakov headed the ultimately decisive goal in the 36th minute.
More police were brought in to control the situation but seats and punches were thrown in clashes that continued during the half-time interval.
The police had earlier needed to separate rival sets of supporters outside the ground.
Tottenham pledged to fully support Uefa and the Spanish and British authorities as the investigation into the trouble got under way.
A club statement read: "The club will be working with the appropriate authorities to ascertain the events of this evening in Seville.
"Our initial reports suggest there was no fan-to-fan fighting at any stage of the proceedings.
"As such we are seeking explanations as to why the police reacted in the way they did with our fans.
"Tottenham Hotspur supporters have enjoyed an exemplary reputation across Europe this season which is why the events are unprecedented.
"We will be co-operating fully with UEFA, the British Embassy and the Spanish authorities to understand why this has happened.
"British Police, the club's security officials, and club stewards - supported by British Embassy officials - will also be providing the Spanish authorities and UEFA with full statements from their first-hand experience of what happened tonight."
Uefa communications director William Gaillard said: "Any incidents of crowd trouble in the Sevilla against Tottenham match will be investigated by Uefa.
"We will study the reports from the referee and the Uefa match delegate."
The incidents echoed events at the Stadio Olimpico in Rome the previous night when police attacked United fans with batons.