An eagle that was almost a double eagle helped Larry Nelson tie Australian Graham Marsh for the first-round lead Thursday in the Senior Players Championship.

Both opened at 6-under-par 66 over the TPC of Michigan, one stroke better than Hale Irwin.

Nelson, 51, seeking his second victory this season on the senior circuit, was 238 yards out when he hit a 5-wood from the fairway of No. 13, a 506-yard, par-5. The ball landed on the front of the green, then curled around the upper shelf, making a U-turn toward the cup.

"I heard the people clapping, so I knew it was pretty close," Nelson said.

As the ball continued to roll, it appeared dead in -- until stopping about a foot from the pin.

"From where I was, I should have made four there," Nelson said. "Clearly, the three was a little extra bonus."

Six players were at 68, including George Archer and Vicente Fernandez. Jim Albus, who won this tournament in 1991, was among five at 69.

Allen Doyle and Bruce Fleisher, who between them have won seven of 18 senior events this season, shot 70 and 72, respectively.

Jack Nicklaus, who designed the 6,966-yard course, shot 71, matching Lee Trevino and Jim Colbert. Defending champion Gil Morgan, who beat Irwin by three strokes last year, shot 74.

Nelson, winner of two PGA Championships and one U.S. Open title during his years on the PGA Tour, parred the final five holes.

"Last year was my first at this course, and I didn't play very well," Nelson said. "But I learned the places on this course to stay away from. That paid off today."

Marsh, 55, winner of this year's Tradition -- also considered a major on the senior circuit -- had a strong finish, making birdie on the final three holes. He also had three birdies on the front side in a bogey-free round.

"It all seemed to come together for me," Marsh said after matching his best round of the season. "I must say, it was a good time for that."

Three of his birdies came on par-3s.

"I just felt I had the right club in my hand, each time," Marsh said. "That's a good feeling. You can just make a free and easy swing. That was the key today, because I really didn't do much on the par-5s."

Irwin, who withdrew from the U.S. Open last week at Pinehurst, N.C., because of a sore left shoulder, credited two physical therapists who regularly travel with the tour for getting him ready to play.

Irwin, 54, chipped in from 40 feet for birdie on No. 14 and went bunker to bunker yet still saved par on No. 16.

"My shoulder gets better every day," Irwin said. "When I came up here Tuesday, there seemed a good chance I might be going back home Tuesday night."

The winner of the $2 million tournament, sponsored by Ford Motor Co., will pocket $300,000.

Divots:

• Irwin's 18 straight rounds of par or better is the best run on the senior tour this season.
• Jim Dent eagled the third and 13th holes. That's the fifth time this season a senior has bagged two eagles in a round.
• The TPC of Michigan isn't an easy course, yet scores are frequently low in this tournament. Marsh said it's because Nicklaus designs greens to reward risk. "If your game is on, and you go for the pin, you'll frequently have a short birdie putt," Marsh said.
• Nelson said he thought scores were low because the course is in such good shape. "It's also not an especially long course. You see a lot of wedges into greens," Nelson said.