Juergen Klinsmann has been on the job for 10 months now, experimenting with lineups and tinkering with formations like a mad scientist attempting to build the perfect beast. Along the way, his U.S. men’s national soccer team has stunned Italy and put forth other encouraging efforts.

Until now, though, the assignments have lacked urgency. Results in friendlies are swell — Saturday’s 5-1 romp over Scotland in front of 44,438 at EverBank Field, among them — but the Americans haven’t encountered the weight of World Cup qualifiers and international tournaments.

Those carefree days, however, are coming to an end, and over the next two years, American soccer will render judgment on Klinsmann, the German free spirit who has promised to infuse innovation and spirit into a firm foundation.

The Scotland encounter began a patch of five matches in 18 days in three countries, culminating with the first two tests in the quest to secure passage to the 2014 World Cup in Brazil.

Employing his strongest roster since being hired, Klinsmann will continue fine-tuning Wednesday against five-time world champion Brazil at FedEx Field in Landover.

After facing Canada in Toronto next Sunday, the Americans will begin play in the semifinal round of World Cup qualifying with a June 8 opener against Antigua & Barbuda (same 82,000 population as Reading, Pa.) in Tampa and a troublesome task four days later at Guatemala.

One of the lingering questions was how Klinsmann would re-integrate Landon Donovan, the program’s all-time leading scorer. Donovan remains a dynamic presence on the American scene but, until Saturday, hadn’t appeared in a U.S. match this year.

The answer was resounding. Donovan recorded his third career hat trick and added a late assist to cap a fast and devastating performance against a wilting opponent. The five-game winning streak is the Americans’ longest in four years.

“Our movement was really good,” Donovan said. “It made it easier for us in attack. If we have attacking space, we are going to score eventually.

With the absence of Clint Dempsey (groin strain) and Jozy Altidore (arrives Monday), Donovan was on the spot to score. Starting on the right wing, Donovan needed all of three minutes to put a stamp on the match. A tight turn tested goalkeeper Allan McGregor, but he pounced on the rebound and fired over two retreating defenders.

Eight minutes later, Michael Bradley’s spellbinding drive doubled the lead.

Jermaine Jones touched the ball back to the Italian-based midfielder, whose 25-yard one-timer with the outside of his right foot swerved beyond McGregor’s reach and splashed into the top right corner.

Geoff Cameron’s own goal in the 15th minute — he inadvertently chested Kenny Miller’s crossing header past keeper Tim Howard — dampened the mood. Cameron, an MLS standout with three previous U.S. appearances, is one of those borderline candidates heading deeper into the qualifying cycle.

Klinsmann also tested German-based striker Terrence Boyd, 21, who had debuted in the Italy game in February, and Mexican-based midfielder Jose Torres, who has shuttled in and out of favor. Both showed qualities, though Boyd’s inexperience in the box was apparent.

Donovan was in supreme form in the second half, running at defenders and applying sweet touches. After his 50th-minute magic was interrupted by the right post, he placed Jones’s cross into the left corner in the 60th and finished Bradley’s perfect through ball five minutes later for his 49th U.S. goal.

In his final wonderful act, Donovan crossed to Jones for a 70th-minute header.

U.S. notes: The Americans will practice at the University of Maryland’s Ludwig Field on Monday at 5 p.m. Parking and admission are free. . . . Attendance was the largest ever for a U.S. friendly in the Southeast U.S. . . . Brazil, which will arrive in Washington on Sunday, began a four-game tour with a 3-1 victory over Denmark in Hamburg. Hulk scored twice in the first half.