Giacomo (search), a 50-1 shot, defied the odds and won the $2.4 million Kentucky Derby in a gigantic upset Saturday, running down a game Afleet Alex in the final strides and generating a huge payoff.

Even though trainer Nick Zito (search) had five horses in the field of 20, including the favorite, George Steinbrenner's Bellamy Road, this Derby belonged to a 3-year-old gray colt who won just once in seven races.

Giacomo, who always managed to stay in contention, finished fourth in the Santa Anita Derby (search), and trainer John Shirreffs was confident his colt would run well in the 1 1/4-mile Derby.

Did he ever.

The winner, named for the rock star Sting's 9-year-old son, was ridden by Mike Smith, who, at long last, grabbed his first Derby victory in his 12th attempt. Smith was also aboard Holy Bull, Giacomo's sire, when he finished 12th in the 1994 Derby.

Bellamy Road, the New York Yankee owner's first real Derby contender, never mounted a serious threat and finished seventh.

Closing Argument, a 70-1 shot, finished second with Afleet Alex third in the largest Derby field since 20 started in 1984. It was also the richest Derby ever run, up from $1 million last year.

The wild results produced the second-highest win payoff in Derby history. Giacomo returned $102.60 on a $2 win ticket. The Derby record is $184.90 by Donerail in 1913.

Under gorgeous sunny skies, and with the second largest crowd in Derby history — 156,435 — roaring as the field turned for home, it appeared as if Afleet Alex was on his way to a victory.

But Giacomo came on with a rush and won by a half length.

The winning time for the race was 2:02.75.

Zito, who saddled one quarter of the field, has to be wondering if he'll ever have a better chance at winning his third Derby.

Earlier in the week, Zito said: "If we don't get No. 3 now, then I'll have to have Secretariat himself."

When it was all over, he said: "I thought I was in good shape. Obviously, it wasn't our day, and that's what makes racing. It was a great experience, but a great disappointment."

Shirreffs became the third straight trainer to win the Derby on his first try. John Servis won with Smarty Jones last year, and Barclay Tagg won with Funny Cide in 2003.

Bellamy Road's disappointing finish comes three weeks after an astonishing 17 1/2-length win in the Wood Memorial.

The result probably won't lift the Boss's spirits, even though the Yankees ended a four-game losing streak with a 5-0 win over the Oakland Athletics on Saturday.

Don't Get Mad was fourth, followed Buzzards Bay, Wilko, Bellamy Road, Andromeda's Hero, Flower Alley, High Fly, Greeley's Galaxy, Coin Silver, Greater Good, Noble Causeway, Sun King, Spanish Chestnut, Sort It Out, Going Wild, Bandini and High Limit.

Giacomo also returned $45 for a place bet and $19.80 to show. Closing Argument, ridden by Cornelio Velasquez, paid $70 and $24.80. Afleet Alex, with Jeremy Rose aboard, paid $4.60.

If Giacomo goes on to win the Preakness in two weeks, the stage would be set for a fourth straight Triple Crown try in the Belmont Stakes on June 11. War Emblem in 2002, Funny Cide and Smarty Jones each won the Derby and Preakness, but came up short in the Belmont.

Owned by Rondor Music chairman Jerry Moss, who also co-founded A&M records, Giacomo earned $1,639,600 in the richest Derby ever, boosting his bankroll to $1,866,316. Moss's friendship with Sting dates back to when The Police, his band, was involved with Moss's label.

This Derby started out being all about Zito and his Fab Five entries. From the minute Bellamy Road won the Wood, there was no doubt Steinbrenner's colt would be the Derby favorite.

While Zito kept saying the race was not a given — "There are 20 horses in the race, and the other 15 guys aren't rooting for us" — he was confident he had the best Derby chance.

But it wasn't to be. Bellamy Road's finish was the best Zito's horses could do. Andromeda's Hero was eighth, High Fly was 10th, Noble Causeway 14th and Sun King 15th.

"I'm human like everybody else, but it's going to be a little bit of a setback. When you start thinking about what happens in life, this ain't that bad," Zito said.

Giacomo, breaking from the No. 10 gate, was a little wide around the turn and started making up ground at the top of the stretch. Smith guided Giacomo outside and the colt took off, moving past Afleet Alex for the shocking victory.

"It's awesome," Shirreffs said.

Smith agreed: "When I stood up at the wire, all the strength left my body and I was hanging on for dear life."

In the 1994 Derby, Holy Bull went off as the favorite, but never really had a chance. Who won? Zito, with Go for Gin.

"Giacomo redeemed his father's name," Smith said.

Giacomo's only other victory in eight starts was back on Oct. 22.