There are few things as bad as injured strikers going into a World Cup campaign

Spain's Diego Costa, second left, and Sergio Busquets, left, duel for the ball during a training session at he Atletico Paranaense training center in Curitiba, Brazil, Tuesday, June 10, 2014. Spain will play in group B of the Brazil 2014 World Cup. (AP Photo/Manu Fernandez) (The Associated Press)

Belgium's Romelu Lukaku touches his ankle during a friendly soccer match against Tunisia, at the King Baudouin stadium in Brussels, Saturday, June 7, 2014. Belgium will play against South Korea, Russia and Algeria in Group H of the World Cup 2014 in Brazil. (AP Photo/Yves Logghe) (The Associated Press)

MOGI DAS CRUSES, Brazil – To understand just how precious a team's top forward is, simply look at the coaches' frowns when one is hobbling or grimacing during World Cup preparations.

Or the relief when an injury doesn't appear to be as bad as feared.

So when Romelu Lukaku was performing balancing drills on his right ankle without any negative effect on Wednesday, Belgium could take a sigh of relief — its top striker looked fully fit again.

The same goes for defending champion Spain, which now has good hope of recovering Diego Costa for its hotly anticipated rematch of the 2010 final against the Netherlands on Friday.

"He's ready," said Spain midfielder and Atletico Madrid teammate Koke. "He looks 100 percent to me."