Click photo to enlarge
Ryan Hall of the United States passes Buckingham Palace early in the marathon but ended up dropping out due to a hamstring strain Aug. 12, 2012, at the 2012 London Olympic Games.

LONDON -- Ryan Hall, the former Stanford All-American, had never quit a race before.

Ever.

But on a warm Sunday morning, Hall, 29, walked off the Olympic men's marathon course along the famed Pall Mall, shaking his head and filled with what-ifs after suffering a right hamstring muscle strain.

America's leading marathoner now has a "DNF" in his resume after disappointment on the final day of the London Games.

Former training partner Meb Keflezighi of Mammoth Lakes placed fourth by using a strong kick to finish in 2 hours, 11 minutes, 6 seconds. He was 3:05 behind surprise gold medalist Stephen Kiprotich of Uganda, who won in 2:08:01. Abel Kirui of Kenya won the silver medal in 2:08:27, with early leader Wilson Kipsang Kiprotich of Kenya taking the bronze in 2:09:37.

Hall, who lives in Redding, had never finished worst than 10th in a marathon. That was his place at the Beijing Games. But Sunday it got to the point where place wasn't as important as just surviving.

"Honestly I'm a little bit in shock right now," Hall said. "There's no positive. I just have to keep trying to move forward."

With that he walked off arm-in-arm with wife Sara Hall, also a former Stanford All-America runner.

Abdi Abdirahman of Tucson, Ariz., felt his right knee pop and he also dropped out -- like Hall just after 10 miles into the 26.2-mile ordeal.

"I tried to go a couple of more miles," Abdirahman said. "I just couldn't take it anymore. Just painful."

Hall has been struggling with injuries since securing his spot on the Olympic team in January. He had plantar fasciitis for seven months, leading him to favor his left foot. Then the hamstring muscle started bothering him a few months ago.

"As marathoners you train so hard, you're pushing the body so hard these things come up," he said.

Hall, who trains without a coach, tried to continue in the heat of the day but said the hamstring muscle got progressively tighter the more he ran. Soon he had to make a painful decision: finish the Olympic race and risk serious injury or walk away.

"It's really disappointing, but I'm trying to keep the overall big-picture perspective," Hall said. "I'm just trying not to do anything stupid out there, trying not to damage my body."

Hall has never been afraid to go his own way. In October 2010, he left the elite Mammoth Track Club run by respected coach Terence Mahon.

The deeply religious Halls moved to Redding to join the Bethel Church, a faith-healing congregation. Hall has said he doesn't need a coach because of his devotion to Christianity.

Although some have suggested Hall's methods are unorthodox, he has emerged as America's most promising marathoner. Hall finished third in 2009 and fourth in 2011 at the Boston Marathon, where he had a time of 2:06:17.

But it is Keflezighi who has done as much as anyone since Frank Shorter to keep Americans in the conversation of international distance running. Keflezighi, 37, won a silver medal at the Athens Games but failed to make the 2008 U.S. team.

He woke up Sunday feeling good despite suffering from a gluteus injury in April when he could barely walk. Two more weeks of training and Keflezighi might have been ready to repeat the 2004 medal performance, he said.

"Did I want to finish fourth?" Keflezighi asked. "It's not where you want to be sometimes, but in my last Olympics I'll take it."

He had reason to be satisfied on the final footsteps of a two-decade career. Keflezighi has had a marathon journey. He came to San Diego with his family at 12 as an Eritrean refugee. The father of three became one of Southern California's best high school runners before becoming a UCLA All-American.

Although he might have been the happiest fourth-place finisher in London, Keflezighi was in a foul mood at the starting line after being overlooked in the introductions. Race organizers highlighted about a half dozen of the favorites.

"Only two people in the world have an Olympic medal and a New York win," he said.

Keflezighi, wearing a white cap, white singlet and red shorts, was among the leaders in the early stages of the course that snaked its way through central London's landmarks. Although he couldn't hang close to the leaders, the race in front of him was as dramatic as expected.

But the winner was far from anticipated. Kiprotich won Uganda's second gold medal in history, the first since John Akii-Bua was first in the 400 hurdles in 1972.

The medal was Uganda's first in any sport since the Atlanta Games in 1996.

Kiprotich made a decisive move with three miles left, then accelerated in the final mile to stave off the Kenyans.

With a 26-second cushion, the winner grabbed a Ugandan flag from the stands and wore it across the finish line on a day thousands of spectators swarmed the city to celebrate the end of the 2012 Summer Games.

"At the start, I didn't believe I could win the race," Kiprotich said.

At the exhausting end, everyone watching knew he could.