HARRISON, N.J. — Jurgen Klinsmann has been preparing for World Cups long enough to know not to show his hand two weeks before the opening game. Not to reporters, certainly. But not to his players, either. So he tinkers with his lineups and his tactics, and he generally keeps his opinions to himself.

In that sense, Sunday’s 2-1 victory against Turkey at Red Bull Arena was just 90 more minutes for him to study. To check and recheck what he has seen during weeks of training sessions, and to find the best possible starting lineup for the Americans’ World Cup opener against Ghana on June 16.

“The fine-tuning element is coming along; it’s getting better,” Klinsmann said in a typically blind review of the performance. “It’s not where we want it yet, there’s no question about that, but we’re working on it.”

Yet each game reveals new clues that Klinsmann knows exactly what he wants. He made only three changes to his lineup Sunday from the one he started in last week’s 2-0 victory over Azerbaijan. The results were mixed.

Fabian Johnson scored the United States’ first goal off a pretty chip from Michael Bradley in the first half, and Clint Dempsey added the second after an ugly defensive miscue by Turkey. But the center of the American defense was repeatedly tested in a shaky first half, and Timothy Chandler struggled with composure and giveaways in a rough 90 minutes at left back.

Turkey had so many chances in the first half that Klinsmann was forced to alter his preferred diamond midfield formation at halftime, dropping Bradley to create more of a flat 4-4-2. That plugged a few gaping holes down the center, but it also allowed Turkey to shift its focus to attacking Chandler’s side. He was not punished until the 90th minute, when his momentary lapse of concentration created a chance that led to a penalty kick, which Turkey converted.

Several players helped themselves, though, among them Dempsey, who returned to the starting lineup after sitting out the first game of the Americans’ send-off tour because of groin stiffness, and his strike partner Jozy Altidore. Central defender John Brooks was the biggest surprise, turning in perhaps his strongest game for the national team as a second-half substitute.

Brooks, 21, has played only four times for the United States, and he is one of several players who know they must grab every opportunity to impress Klinsmann if they are to force their way onto the field in Brazil. Another, the 18-year-old midfielder Julian Green, made a half-hour cameo in the second half.

“I’m just trying to make the decision as hard as possible,” Brooks said.

Altidore might have been the biggest winner Sunday, working tirelessly alongside Dempsey for 90 ball-hawking minutes. Turkey’s coach, Fatih Terim, described Altidore as “the kind of striker center backs don’t like very much.” Holding up play to build attacks, and giving as good as he got when it came to fouls, Altidore did everything but find his way onto the scoresheet.

Altidore appeared to score in the 15th minute, but the goal — which would have been his first in any competition since December — was disallowed because of contact with the goalkeeper. Later in the first half he was fouled after stripping a defender deep in Turkey’s end, and in the second he failed to convert on a handful of dangerous opportunities.

He passed up his last chance to score — crossing instead of shooting in the 79th minute — but his work pleased Klinsmann.

“He had his opportunities today and his chances and we’re waiting for it,” Klinsmann said of an elusive Altidore goal. “I wouldn’t mind if the goal comes against Ghana right away. But it is the Jozy we want to see.”