MEXICO CITY -- Jeff Van Gundy warned the Americans that they were in for a serious challenge.

To his chagrin, he was right - and the U.S. was handed a rare loss.

Francisco Cruz scored 24 points, Mexico opened with an 18-0 run and went on to beat the United States 78-70 on Thursday night in a qualifying game for next year's FIBA World Cup.

According to USA Basketball, it was just the second loss by the U.S. in 30 games against Mexico - with the other defeat coming in the 2011 Pan Am Games.

Orlando Mendez-Valdez added 20 points for Mexico, which held the U.S. scoreless for the first 5:51 and forced the Americans into missing their first 10 shots from the floor.

Marcus Thornton scored 14 points for the U.S., which is using a roster composed primarily of G League players for the qualifying rounds. Xavier Munford added 11 points while David Stockton and Reggie Hearn each had 10 for the Americans.

The U.S. lost for the first time in 10 contests under Van Gundy, who is coaching this team that's tasked with getting the team of NBA stars that will be coached by Gregg Popovich to the World Cup.

"We can't underestimate how hard it is going to be to play on the road, at altitude, and against a team desperate to qualify for the FIBA World Cup," Van Gundy said leading up to the game. "We have to make sure we match that type of intensity and passion that we know they'll bring."

By the time the U.S. found its stride, it was already in deep trouble. Mexico led 31-10 after the first quarter, then staved off a big second-half rally try by the U.S.

Trey McKinney-Jones' basket late in the third quarter capped a 15-1 run and put the U.S. within 53-51. Thornton made a pair of 3-pointers about a minute apart in that burst, and Hearn's 3-pointer early in the fourth cut Mexico's lead to 56-54.

But the U.S. never got the lead.

The Americans (4-1) - who have already ensured a spot in the second round of qualifying that starts in September - end the first-round series of games Sunday when they go to Havana to face Cuba (0-5). It'll be the first time a U.S. men's national team has played in Havana since the 1991 Pan American Games. Mexico (3-2) also wraps up its first round on Sunday, when it plays at Puerto Rico (3-2).

David Huertas had 18 points, Angel Rodriguez and JJ Barea each had 15 and Puerto Rico rallied in the fourth quarter in another qualifying game Thursday to top Cuba 84-80.

Under FIBA's new qualifying format, teams are playing home-and-home games against teams in their region to earn places in the World Cup in China, which begins on Aug. 31, 2019. That tournament will qualify seven teams for the 2020 Olympics in Tokyo.

This was the first time the U.S. played a true road game during this tournament. The Americans opened qualifying in November with an 85-78 win in what was a "home" game for Puerto Rico - but the contest was actually played in Orlando, Florida because of continued problems in San Juan following Hurricane Maria.

And this was very much a real road atmosphere.

Not only was the game played at Mexico City's 7,500-foot altitude, but in a filled 5,000-seat arena that Mexican officials said sold out in only 45 minutes.

The tone was set by the U.S. turning the ball over on each of its first three possessions, and Mexico was off and running.

The U.S. routed Mexico back in November, winning by 36 points.

That was a very different Mexico team.

Only four players from the Mexican roster then were in uniform on Thursday night, with the team now able to add those who were playing in their various professional leagues and unable to take part when the qualifying rounds began. Cruz and Mendez-Valdez each had 13 points by halftime, and Gustavo Ayon was a big factor even without big numbers - four points, four rebounds and five assists by the break.

If their names are familiar to U.S. basketball aficionados, it's for good reason.

Ayon appeared in 135 NBA games in parts of three seasons with four different franchises, and just helped Spanish powerhouse Real Madrid win the EuroLeague. Mendez-Valdez was part of the Western Kentucky team that went to the Sweet Sixteen in 2008, and he won the Sun Belt's player of the year award in the following season. Cruz played at Wyoming and has played in pro leagues in Mexico, Latvia, Argentina and Spain.