By Jack Stubbs

RIO DE JANEIRO (Reuters) - Jeff Henderson of the United States won gold in the men's long jump on Saturday, leaping 8.38 meters to snatch the title in the last round.

His win, edging out South Africa's Luvo Manyonga in the last round of the competition, gives the United States its 22nd long jump gold medal.

"It feels good to be in that category, to win that many medals. It feels surreal right now," Henderson told reporters at a news conference alongside Manyonga and dethroned London 2012 champion Greg Rutherford of Britain who took bronze.

As the reigning Olympic, World, Commonwealth and European champion, Rutherford had been favorite ahead of the Games.

In 2012 he stormed to the top of the Olympic podium in what British media later dubbed 'Super Saturday' when three British athletes win gold in the space of an hour.

But in Rio he scraped into the final, qualifying in 10th place, and could only jump 8.29 meters in the bid to defend his title.

"I never thought in my career I'd be disappointed with a bronze medal but I'm gutted," the 29-year-old told reporters, tears streaming down his face.

"Ultimately I didn't jump long enough today and that's very difficult for me to take," he said. "I've won a lot and today I haven't won, it's something I'm not used to."

Henderson and Rutherford put themselves ahead of the pack early in the competition, both jumping more than eight meters on their first attempts.

But Manyonga, who fouled two of his first three jumps, shocked the Brazilian crowd and his competitors with a distance of 8.28 meters in the fourth round.

Invigorated, the 25-year-old then flew 8.37 meters on his next attempt, putting him on course for Olympic gold.

"I knew I had something big in me. I felt it in me, it was growing inside," Manyonga said.

"I wanted to get more. If there was an extra jump, a seventh jump, I promise you, it would have been a massive one."

Henderson's victory was secured with his last jump, overhauling the South African by just one centimeter.

His American team mate Jarrion Lawson looked set to stage a last-minute upset and take a place on the podium, but a trailing hand in the sand cost him a medal.

"It felt pretty far," Henderson said of his medal-winning mark. "I knew it was the winning jump."

(Editing by Ed Osmond/Greg Stutchbury)