ISTANBUL, (Reuters) – Serbia and Croatia won a haul of medals when they were partners in the former Yugoslavia but today they will face each other for the first time as  independent nations in the world championship last 16.

Passion will also be running high when holders Spain take on Greece, also today, in a repeat of the 2006 final.

Favourites the United States play Angola on Monday while  Argentina and Brazil lock horns in a South American derby on Tuesday.

The Serbians have had more success than the Croats since the two nations parted company in 1991 and their contrasting form in Turkey suggests Serbia will start as strong favourites to reach the quarter-finals.

“Unlike us, Serbia have played outstanding basketball in  this tournament and we can only beat them if we double our efforts,” Croatia forward Kresimir Loncar said after their 92-74  rout by Brazil in the final Group B match on Thursday.

“We looked like we had never played together before and our current form is not good enough to give much weaker teams than Serbia a run for their money.”

Serbia, who lost to Spain in the 2009 European Championship  final, won Group A with an enthralling 84-82 Group A win over  2004 Olympic champions Argentina but their coach Dusan Ivkovic  said they had to improve in the knockout rounds.

“We have to make sure we don’t concede easy points and  commit silly fouls any more, our fast-flowing game sometimes  backfires because this is a young team,” he said.

“But overall I am proud of my players because they have  shown moderm and entertaining basketball in high-scoring games,  which the fans love to watch.”

Serbia are the tournament leaders in points, assists, and  rebounds per game, their only glitch coming in an 82-81 defeat by eliminated Germany when they had captain Nenad Krstic and  playmaker Milos Teodosic suspended.

The Spaniards are sorely missing Los Angeles Lakers centre Pau Gasol and Toronto Raptors playmaker Jose Manuel Calderon and their depleted side had a rough ride in the preliminary stage, losing to Lithuania and France in Group D.

The United States breezed through the group stage and  although beating Angola in the last 16 should be a formality, their coach Mike Krzyzewski said the overall performance still  left something to be desired.

“The Tunisia game was symbolic of the level of hard play in every possession in our pool,” he said after his team coasted to a 92-57 whitewash of the Africans.

“They got 25 offensive rebounds and that means they never  gave up on the ball; I admire that and it means we have to work  on our stuff a little bit better.”

Argentina have been the dominant South American team since  they reached the 2002 final in Indianapolis, followed by their  2004 Olympics victory when they beat the United States in a  memorable semi-final.

But Brazil, led by Argentine coach Ruben Manano and aiming  for their first World Championship medal since 1978, will not be  overawed after upsetting their perennial rivals in the South  American Championship final earlier this year.

The remaining last 16 matches feature Slovenia against  Australia, Turkey against France, Russia against New Zealand and  Lithuania against China.