|A Serbia fan is dragged away by a security man in the friendly hosted by Austria [AFP]
Serbia's stand-in captain Nemanja Vidic intervened to allow his side's friendly defeat against New Zealand to finish in Klagenfurt, appealing for calm over the public address system as Serbian fans rioted.
Trouble erupted in the second half when Serbian fans threw missiles on to the pitch.
The match was held up for several minutes, with New Zealand players and the officials preparing to walk off, before play resumed. Serbia lost 1-0.
Cameroon captain Samuel Eto'o threatened to stay away from the World Cup, while Diego Maradona, another man who has endured a turbulent relationship with his national side, got a lively send-off as Argentina left for South Africa.
Eto'o, who helped Inter Milan to win the European Champions League final last weekend, took umbrage at remarks by Cameroon's 1990 World Cup hero Roger Milla, who said the striker had done little for the national side.
"Is it worth me going to the World Cup?" Eto'o asked on French television channel Canal Plus Sport.
"I still have a few days to think about it but I will see if my participation is important because I don't need this in my career."
Eto'o did not play in Cameroon's 1-1 draw with Slovakia in a friendly in the Austrian town of Klagenfurt on Saturday but he was later named in Paul Le Guen's final 23 for the tournament.
Milla scored four goals to help the Indomitable Lions reach the quarter-finals in Italy. Since then, the team have fallen at the group stage in three World Cups and failed to qualify for the 2006 finals.
Maradona, as player and now coach, has had his ups and downs with Argentina but fans were enthusiastic as the team headed for Buenos Aires international airport.
Slovakia lost their most experienced player, Miroslav Karhan, when the defensive midfielder was ruled out of the June 11-July 11 finals after being told on Saturday that he needed three weeks off to recover from a hamstring injury.
"I am very disappointed, it is hard to say more," said Karhan, who has 96 international caps.
The United States, worried about a string of injuries among their defenders, came from behind to beat Turkey 2-1 in Philadelphia with goals from Jozy Altidore and Clint Dempsey in their last game on home soil before the finals.
Spain, among the favourites for the World Cup after their success at Euro 2008, also had to scrap for a victory in their game against Saudi Arabia in Innsbruck, eventually grabbing a 3-2 victory thanks to a last-gasp strike from Fernando Llorente.
David Villa and Xabi Alonso had scored their other goals.
Three-times World Cup winners Germany had no such problems, as they enjoyed a 3-0 win over Hungary in Budapest with goals from Lukas Podolski, Mario Gomez and Cacau.
The main plus point for Germany was the form of Sami Khedira, who excelled in the midfield role left vacant by the injured Michael Ballack.
England named striker Darren Bent and midfielder Tom Huddlestone to the team to face Japan in a friendly on Sunday as manager Fabio Capello tried to decide on his final squad before Tuesday's deadline.
In South Africa, Fifa president Sepp Blatter attended the official opening of the Peter Mokaba World Cup stadium in Polokwane and declared himself delighted with ticket sales and with the form of hosts South Africa since Brazilian coach Carlos Alberto Parreira returned to lead the team.