SCOTTSDALE, Ariz. — A capacity crowd of 16,000 surrounded an otherwise innocuous par-3 16th hole at TPC Scottsdale on Wednesday during the pro-am of the Phoenix Open, which begins Thursday, having gathered to watch Michael Phelps and his pro partner, two-time major winner Jordan Spieth. The crowd was nearly the size of the ones that witnessed Phelps' record eight gold medal swims at the 2008 Olympics at Beijing's Water Cube.
Phelps, who won 28 medals, including 23 gold, over five Olympics before retiring after last summer's Rio Games, stopped on his way to the tee box to pose for photographs with tournament volunteers clad in red, white and blue outfits and wearing 23 gold medals, purchased in bulk online for $4. In some cases, they wore white and blue men's swimsuits over their pants.
As Phelps autographed a "quiet" sign held by Mary Anderson, the costume mastermind, he told her, "I am shaking so hard right now."
His first shot landed left of the green, and Phelps pre-empted any booing by dropping his club and turning his thumbs down. At the crowd's urging, he took a mulligan, which also missed.
Recording the whole scene with Phelps' phone was Spieth, a former world No. 1. On this day, he was happy to cede center stage to Phelps, who was often late arriving to the tees because he was signing autographs and taking photos with fans.
The round felt like the latest lap in Phelps' post-career parade, which shows no signs of petering out. Phelps' wife, Nicole, who walked the 18 holes with the couple's 9-month-old son, Boomer, in her arms, took in the cheers and said, "This is good for Michael."
Spieth, ranked No. 6 in the world, also took a moment to revel in the scene. "If you think about it, he's the most decorated Olympian ever," Spieth said. "He could be argued as the greatest champion in sport, right? So that's very cool. I mean, it's amazing."
Phelps' son has his own ardent fan base, with 774,000 Instagram followers, and spectators gave him shout-outs on every hole. At the 14th, a woman with her smartphone camera trained on the group cooed, "What a cutie." Spieth seemed surprised, however, upon realizing the fan was referring to him, not Boomer.
"I thought she meant the baby," said Spieth, who soon took a selfie with Boomer and posted it to his Instagram page.
The pairing of Phelps, 31, with the 23-year-old Spieth was a match made on Madison Avenue. Both are brand ambassadors for the same apparel company, but until they met for dinner Tuesday at Phelps' house near the course, they had never had a lengthy conversation. "I'm surprised we hadn't really crossed paths yet," Spieth said.
But they made up for lost opportunities during the multicourse meal. Spieth told Phelps, who won five golds and a silver in Rio, that he regretted pulling out of last summer's Olympics, to which golf returned after a 104-year absence. And Phelps asked Spieth about last year's Masters, where Spieth frittered away the lead on the 12th and 13th holes on Sunday.
"His response was so great," Phelps said. "For someone so young, to have such a good head on his shoulders. He's a competitor. He wants to be the best, and you see it. He can be so hard on himself. I can relate to that."
The group's collective competitiveness was on display on the 15th and 16th holes. On the 15th, Phelps' caddie forgot to retrieve his golf bag from the middle of the fairway, and Spieth's caddie, Michael Greller, gave Spieth a bad number for his second shot.
"I think both our caddies are getting nervous about the 16th hole," Spieth said.
Phelps grew quiet as he waited for his turn to hit. After he was introduced, he dropped his club, leaned over and swung his arms behind his back twice like he used to do on the blocks before swimming races.
After the hoopla from Phelps' turn had died down, Greller stepped to the tee and, with Phelps serving as the announcer, hit the green with his tee shot. Greller described the shot as "the highlight of my golf career."
Spieth said he has seldom seen Greller, who planned to have Phelps sign the ball he used to hit the shot, so happy — except, perhaps, at Greller's wedding, Spieth said, and maybe during Spieth's two major wins. "But it was up there," Spieth said, laughing.
Lending added star power to the group inside the ropes was swimmer Allison Schmitt, an eight-time Olympic medalist who is pursuing her master's in social work at Arizona State. She walked with Phelps' wife and helped with Boomer.
Spieth seemed shocked when he was told about Schmitt's accomplishments. "You wouldn't know," he said. "She'd never tell you."
At the end of the round, Phelps and Spieth exchanged phone numbers, and Phelps, who was headed to the Super Bowl in Houston for more sponsor appearances, promised to keep in touch.
"He's offered to continue to advise or help or just really anytime I want to reach out, which is just incredibly kind," Spieth said, adding, "I certainly should take advantage of it."