Usain Bolt kneeled down and gave the track one final kiss, then flattened his hand, reached to the ground and slapped the white number “3’’ painted at the finish line.

Three Olympics, three races at each, three gold medals every time.

He could have just as easily slapped the number “1.” That would need no explanation.

The man who transcended track and became a world-class celebrity bid a blazing-fast farewell to the Rio de Janeiro Games — and, he insists, the Olympics altogether — Friday night with yet another anchor leg for the ages. He turned a close 4×100 relay race against Japan and the United States into a typical, Bolt-like runaway, helping Jamaica cross the line in 37.27 seconds.

“There you go,” he said. “I am the greatest.”

Japan won the silver medal, finishing .33 seconds behind.

The U.S. finished the race third but endured yet another relay debacle — disqualified because leadoff runner Mike Rodgers was ruled to have passed the baton to Justin Gatlin before the start of the first exchange zone. That promoted Canada to the bronze medal. The Americans were protesting the ruling, and as 3 a.m. Saturday approached in Brazil, there was no word on the outcome.

“It was the twilight zone. It was a nightmare,” said Gatlin, who, along with his teammates, found out about the DQ while parading the U.S. flag around the track. “You work so hard with your teammates, guys you compete against almost all year long. All that hard work just crumbles.”

If the ruling stands, it will mark the ninth time since 1995 the U.S. men have been disqualified or failed to get the baton around at the Olympics or world championships. (They blew a 10th medal, the silver at the London Games, after Tyson Gay’s doping positive.)

The disqualification will cause more hand-wringing in the States.

In Jamaica, they’ll party.