Spain's 2-1 World Cup qualifying win over Belarus in Palma de Mallorca on Friday night took Vicente del Bosque's men to the brink of next summer's finals in Brazil, but left unanswered many of the questions currently hanging over the current trophy holders.

Tellingly, while the atmosphere inside the Estadi Son Moix was carnival-like for a key World Cup qualifier at kickoff, as few expected the visitors to pose much of a challenge, by the end of another lackluster Spanish display, the home fans were urging the Dutch referee to blow for time.

In short, the World champions were again lacking in real drive and energy. It took an hour for Xavi Hernandez's neat strike to open the scoring, and substitute Alvaro Negredo's diving header should have settled things, only for Sergei Kornilenko to take advantage of some poor defending and cause a late scare.

The result means a draw against Georgia in Albacete on Tuesday seals direct qualification for the finals. While Spain will surely get that at least -- it should never really have got so close.

This is del Bosque's third qualifying campaign as boss. During the first two his team won every qualifier -- home and away --- but this time things have been tighter, with shock 1-1 home draws against both France and Finland. The uncertainty around the team then heightened when Brazil swept them aside 3-0 in June's Confederations Cup final.

Del Bosque has been gradually evolving the side over his five years. There is no need for a huge change now, with Andres Iniesta, Sergio Busquets, Cesc Fabregas, Gerard Pique, Sergio Ramos, David Silva and Pedro Rodriguez all hugely experienced and still the right side of 30. But form and fitness concerns surround previous pillars including Iker Casillas, Xabi Alonso, David Villa, Fernando Torres, Carles Puyol and even Xavi himself ahead of next year's finals.

Video: Did Diego Costa make the right decision choosing Spain?

Del Bosque showed on Friday that he shares these worries -- with Swansea City 's Michu a surprise pick to win his first cap. You could see the thinking -- a more physical presence, a new call-up with more enthusiasm and energy. Something especially useful against teams who -- as almost all Spain's opponents do -- pack their defenses and sit deep. However Michu often looked on a different wavelength to his teammates, and headed his only real chance well wide before being withdrawn with the game still scoreless.

This had the look of a preliminary trial however, and even though Negredo scored from the bench, Diego Costa will likely get a chance in a roving frontman role once FIFA give his switch from Brazil the all-clear. The Atletico Madrid striker is currently La Liga's top scorer - but this move is about more than just goals. Knowing Spain were bullied by Brazil last summer del Bosque wants a more physical edge to go with their tiki-taka. The super-aggressive Costa brings that.

Del Bosque also showed a willingness to change in goal, where current Madrid back-up goalkeeper Casillas was benched for Barcelona 's Victor Valdes, who should now really continue as first choice. In defense Arsenal 's Nacho Monreal was slightly unlucky to get hooked at halftime as del Bosque made an attacking change -- but the injured Jordi Alba's driving runs from left back were badly missed.

Monreal's replacement was Iniesta, originally on the bench due to a fitness concern, and his introduction did perk things up a bit -- with some typical driving runs and perceptive passes. Fellow midfielders Fabregas and Silva looked neat and tidy but mostly played in front of the visitors massed ranks.

Atletico Madrid's Koke for Fabregas was del Bosque's final change. And while the 21-year-old midfielder will not enjoy replays of Belarus' goal, it is significant that he has now played in all four games since making his La Roja debut in August.

Costa, Koke -- and other youngsters such as Isco, Dani Carvajal and Thiago Alcantara -- should get chances to impress in upcoming friendlies, with del Bosque likely to keep trying new ideas. The veteran coach may have to tell some old friends they are no longer needed.

Having said all that Xavi, quiet in the first half, showed wonderful technique and a decent sense of timing to arrow in the first goal when it was needed. It was a message, perhaps, that Spain's old guard are not done yet.

The world champions are now -- barring the disaster of disasters on Tuesday -- sure to be among the top seeds in December 6's group stages draw in Salvador de Bahia. But del Bosque's upcoming selection choices will be crucial in determining whether they can reach and win the final on July 13 at Rio de Janeiro's Estadio do Maracana.