By Neil Maidment
SALVADOR, Brazil, June 29 (Reuters) - The United States' declaration of their attacking intentions may awaken the more thrill-seeking instincts of unbeaten but so far underwhelming Belgium as they prepare for "war" in Tuesday's last-16 World Cup clash.
The Belgians came through the group stage with three wins from three against Algeria, Russia and South Korea but failed to hit the heights expected of their exciting, star-studded squad with somewhat lukewarm performances and late shows.
However with talents likes Eden Hazard, Kevin De Bruyne and Romelu Lukaku there is time for that to change and the Europeans will be a stiff test for a U.S. side that surprised many by beating off 2010 quarter-finalists Ghana and Cristiano Ronaldo's Portugal to qualify alongside Germany in Group G.
The American's mix of organisation and physical fitness has been improved by coach Juergen Klinsmann's focus on quick passing moves that have sharpened their attacking edge, and it is that high energy mantra that could unsettle Belgium.
"Physically they are very strong. We are preparing for a war," Belgium coach Marc Wilmots told reporters.
A fast start could be key to the progress of the U.S. who will have noticed that Belgium took until at least the 70th minute to score in all three of their group matches.
"We are going to take it to them," said Klinsmann, whose players' families have been told to change flights home until after the World Cup final. "We believe we have enough confidence now going into this game to beat them. We know we have to go to our extremes to make this happen."
While the Belgians may have stuttered slightly, an unbeaten qualifying campaign extended to their first three World Cup games is enviable and does support their ranking as fifth favourites with bookmakers going into the tournament.
A defence possessing Thibault Courtois in goal and dominant centre half Vincent Kompany have conceded just once in Brazil - a penalty to Algeria - and despite their 'dark horse' tag appear unperturbed by a void of anticipated flair in their displays.
"What does it mean to play beautifully?," Wilmots said.
"Every game is characterised by tactics and physical fitness. What is important in the end is the result, to win the match with whatever style of play."
The Belgians have won the last four of their five games with the U.S., including a 4-2 victory in Cleveland in May last year. A solitary win for the U.S. came in the 1930 World Cup.
Having sealed a last 16 spot after two group games, Wilmots fielded a much changed side in Belgium's final tie with South Korea, meaning there will be many fresh legs for the U.S. clash with the line-up expected to revert to that which faced Russia.
Both Kompany and fellow defender Thomas Vermaelen are expected to play despite recent injuries but Wilmots will definitely be without the suspended Steven Defour, as well as injured duo Laurent Ciman and Anthony Vanden Borre.
For the U.S. striker Jozy Altidore is expected to be on the bench after resuming training following a hamstring injury but Klinsmann is unlikely to tinker too much with his line-up.
Toby Alderweireld, Moussa Dembele, Jan Vertonghen and Axel Witsel are one booking away from suspension for Belgium, while the same threat applies to Omar Gonzalez, Kyle Beckerman and Jermaine Jones for the U.S.
The winner of the clash at Salvador's Fonte Nova arena will play Argentina or Switzerland in the quarter-finals. (Additional reporting by Mark Gleeson and Simon Evans, thanks Editing by Nigel Hunt)