Jason Day felt wobbly when he bent over and stood up, when he looked at his target and then back at his ball. One step at a time, he pushed himself around Chambers Bay in the third round of the U.S. Open until he had a 68 and a share of the lead.

It evoked memories of great U.S. Open moments when the champion's toughest test was more than the golf course.

The difference?

Day still had one more round to go Sunday, maybe more if the U.S. Open went to an 18-hole playoff.

Here's a look at five other moments in U.S. Open history when courage, resolve and sheers guts were just as important as chipping and putting:

HOGAN AT MERION: Ben Hogan was the reigning U.S. Open champion when his car collided with a bus in West Texas in 1949, an accident so horrific that it nearly killed him and doctors feared he would never walk again.

Hogan returned to golf a year later and played the U.S. Open at Merion in 1950. He had to soak his legs for an hour each night just to keep playing, and while he was only two shots behind Dutch Harrison going into the 36-hole final day, there were questions whether they could hold up over two rounds.

With Hogan needing a par on the 72nd hole to get into a playoff, his legs were so weakened that he hit 1-iron into the 18th. A plaque at Merion commemorates the shot Hogan hit that led to par, and the photo of his swing is among the most famous in golf. And he won the playoff. Of his four U.S. Open titles, that one meant the most to Hogan "because it proved I could still win."

TIGER AT TORREY PINES: Two days after his runner-up finish at the Masters in 2008, Tiger Woods had arthroscopic surgery to repair cartilage damage in his left knee. He chose not to have his ligaments repaired because he wanted to play the U.S. Open at Torrey Pines. And then a month before the U.S. Open, he sustained two stress fractures of the left tibia.

Woods had not walked 18 holes from the final round of the Masters until the opening round of the Open. The pain arrived without warning after shots, with more frequency deep into the weekend as Woods took the 54-hole lead and limped his way to the finish. Needing a birdie on the 72nd hole to force a playoff, Woods made a 12-foot putt over a bumpy green.

He made another birdie on the 18th hole Monday to extend the playoff, and he beat Rocco Mediate on the first extra hole for his 14th major and third U.S. Open.

Woods had reconstructive surgery a week later and missed the rest of the year.

VENTURI AT CONGRESSIONAL: One of the country's most prominent amateurs, Ken Venturi won eight times as a pro until he hurt his back in 1961 and injured his wrist in a car accident the following year. He missed three straight U.S. Opens until he narrowly qualified for 1964 at Congressional.

It turned out to be an epic final day for the Californian coping with broiling heat.

Venturi shot 66 in the third round but was feeling weak during the break before the final round that afternoon. John Everett, a doctor and member at Congressional, checked on him and found a normal pulse but symptoms of dehydration. He suggested he withdraw because it could be fatal and Venturi said he told him, "Well, it's better than the way I've been living."

He labored to a 70 for a four-shot victory, but he was so weakened by the heat exhaustion and dehydration that he couldn't read the numbers on his scorecard to sign it, the final act before he could claim the U.S. Open. Joe Dey, the USGA executive director, looked over his shoulder at the scores and told him to sign it.

DUTRA'S DYSENTERY: Olin Dutra won the first U.S. Open held at Merion in 1934, and he nearly didn't play. He caught dysentery leading to the championship. He couldn't leave his hotel room, lost 15 pounds and couldn't practice for more than a week.

He decided to play, though a 76-74 start left him eight shots behind going into the 36-hole final.

Dutra shot 71 in the third round to get within three of Gene Sarazen, then made two birdies on the back nine for a 72 to beat Sarazen by one for his second major.

DEATH THREAT AT SOUTHERN HILLS: The record will show that Hubert Green never trailed from the first round and won the 1977 U.S. Open at Southern Hills.

What it doesn't show is a telephone call.

Green received a death threat in the final round. Tournament officials decided to tell him, and Green played on.

"On 15, I hit my second shot in the back of the green — the pin was in the front," Green recalled. "I got over the putt and I'm thinking, 'Am I supposed to be shot?' Hit the putt. Didn't hear anything. I said, 'Chicken.' Didn't say it too loud."

Green closed with a 70 for a one-shot victory over Lou Graham.