The two teams stayed in hotels about four miles apart in the Mediterranean port city and shared the same training ground in Martigues, a canal-side town about 25 miles northwest of Marseille's famous waterfront.
A pre-arranged holiday schedule meant the players were unable to watch each other's games, so on Sunday they traveled 190 miles north to Lyon for Tuesday's final group game against Guinea in Saint-Etienne.
Nonetheless, American soccer synergy was alive and well in Provence.
“We're rooting for them and it's really nice to be here with them,” Zimmerman said. “We both hope to go much further in this competition and hope to see each other again in Paris.”
If results go in their favour over the next few days, both teams will head to the quarter-finals on Friday (men's) and Saturday (women's) at France's most famous football venue, the Parc des Princes in Paris.
The U.S. men's team (1-1-0), second behind France in Group A, could clinch one of two quarterfinal spots with a win. A draw would probably be enough. Even a loss might not keep them from reaching the Olympic finals for the first time in 24 years.
The women's team (2-0-0), already qualified for the quarterfinals, will face Australia (1-1-0) in Marseille on Wednesday in a bid to win Group B.
“I have a great relationship with Walker and have a lot of respect for him as a person and as a player,” Horan said. “We text each other before every game and we wish each other well and the team well.”
“It's really special to have the men's team compete in the Olympics because we haven't had that opportunity in a while,” Horan added. “The fact that both teams can be here in Marseille for a few days and share this experience is part of what makes it so special.”
The U.S. men's team played their first two games at the Stade Velodrome in Marseille, losing to France and beating New Zealand, while the women's team traveled 120 miles east to Nice, where they beat Zambia before returning to Marseille on Sunday to beat Germany, 4-1.
As per tradition, Olympic football will be played throughout the host country and not just in the host city, with Lyon, Bordeaux and Nantes among the seven cities in which matches will be played.
The women's players watched the men's games in the dining room, while the men watched the women's games and even watched highlights in their hotel rooms and treatment rooms.
“It's great that they won. [Sunday]”Obviously, it's something we're proud of,” center back Miles Robinson said. “We're rooting for them.”
Right back Emily Fox is especially interested in Kevin Paredes' performance, and vice versa, as both are from Northern Virginia.
Because the men's tournament is primarily for players under the age of 23, the women don't know the men as well as they do the individual men on the national team (which can all play together).
The exception to the men's team's roster rules is 31-year-old center back Zimmermann, one of three players selected by coach Marko Mitrovic over the age limit.
Two years ago, the 2022 World Cup starter was instrumental in securing a collective bargaining agreement with the USSF that guaranteed pay equality for the women's team after a years-long labor dispute; now, the two teams pool and share prize money from the tournament.
Zimmerman said she was “disappointed” to miss the chance to watch the women's Olympic team event, adding, “I've been trying to get in touch with some of the players, but it's really difficult with the schedule and how quickly they switch between matches.”
After the men's 4-1 win over New Zealand, Zimmerman half-jokingly praised the women's team for scoring three goals in the first half against Zambia, fuelling their fast start.
“We were up 3-0 at halftime and that was probably because we were inspired by the girls,” he said. “We knew they could do it and we wanted to be part of the fun.”
