Now Walsh and May-Treanor are back together on the sand, and they vow to be even stronger than they were when they swept through two Olympics without losing a set.
"We're going to be better, I'm sure of it," Walsh said after the gold medalists began working out together to prepare for the opener of the international tour in Brazil. "Without a doubt, we both are. Individually, for sure. And, collectively, I know we have so much more in us."
Walsh and May-Treanor won gold at the Athens Games in 2004, but after repeating as Olympic champions in Beijing in '08 they both took time away from the sport. Walsh had two babies, and May-Treanor needed about 18 months to recover after tearing her Achilles tendon and calf muscle in 2008 while rehearsing for Dancing with the Stars .
It wasn't until this month that May-Treanor decided she wanted to make a run at London.
"I just needed to step away for a little bit to see what I wanted to do, to see how I felt about it," she said. "It kept eating away. I hit a low point and in my heart I said, 'I need to do this.'
"This is all I've ever known," May-Treanor said. "You never want to live with regret. I'm 33; I still feel that even with the injury I can play at a high level. I feel that I can do this, and that Kerri and I can do this. I didn't want to regret giving up a chance to do something extraordinary."
After discussing it with her husband, Matt Treanor, who is a catcher for the Texas Rangers, May-Treanor then struggled to tell her former partner.
Walsh, 32, had been preparing for the season with Nicole Branagh, who reached the quarterfinals in Beijing with Elaine Youngs.
"You never want to hurt anybody around you. We both like Nicole; we both respect Nicole; we both think she's an awesome teammate. I wish there were more Nicoles in the world," May-Treanor said. "The timing of it was bad, but I don't know if I would have had the strength to say anything earlier."