MANAUS, Brazil — Imagine if an N.F.L. coach never knew when to call for the last-second pass, or an N.B.A. star had to guess when to throw up his desperation half-court shot.

Such situations would be unthinkable in other sports, but vagaries of time are the norm in soccer. Games do not end when a clock expires, but only when the referee decides they are over.

In a world where quantities as varied as footsteps and mouse clicks can be measured with scientific precision, soccer is a land where time remains a mirage. The most recent example came in the World Cup game here Sunday night, when the United States scored to take the lead in the 81st minute of a 90-minute match only to see the advantage slip away when Portugal scored — wait for it — 14 minutes later.

For American players and fans, the late goal was devastating. But it was also confusing. Asked afterward about how long the game had lasted, United States goalkeeper Tim Howard said: “Too long. Thirty seconds too long,” and he was not speaking metaphorically.