LOS ANGELES, July 9 : Spain coach Luis de la Fuente said on Thursday that Belgium would provide his side's sternest test yet in the World Cup quarter-finals, with his team having reached the last eight without conceding a goal.Among the favourites to lift the trophy, Spain booked their place in the quarter-finals with a 1-0 win over Portugal and have grown into the tournament with a balanced side that is comfortable in possession, solid in defence and boasts enough attacking quality to trouble any opponent."Tomorrow's game will be the hardest that we've faced to this point," de la Fuente told reporters in Los Angeles Stadium, pointing out that Belgium's experienced squad includes players with proven pedigree at some of Europe's biggest clubs."Belgium is a very powerful team. These are play