Manager Pep Guardiola said £52m signing Benjamin Mendy will be missing for "two or three weeks" after Manchester City beat Real Madrid 4-1 in Los Angeles.
Mendy, who joined from Monaco, was not involved and will miss the start of the season with a muscle problem.
"We don't want to take a risk because he is so explosive," said Guardiola.
A crowd of 93,000 saw City earn their first win of pre-season with goals by Nicolas Otamendi, Raheem Sterling, John Stones and 17-year-old Brahim Diaz.
In Mendy's absence, Danilo made his debut at Los Angeles Memorial Coliseum, the 26-year-old Brazilian starting at left-back against his former club, having signed for £26.5m.
"Today we saw how good he can play," Guardiola said. "He is a competitor. Him and Kyle helped organise our back four. They communicated with each other. We are very pleased about that side."
City have spent in excess of £200m this summer - England international Kyle Walker (£45m), Portugal midfielder Bernardo Silva (£43m) and Brazilian goalkeeper Ederson Moraes (£35m) joining French full-back Mendy (£52m) and Brazilian Danilo in Guardiola's ranks.
But despite that influx of defenders, it was City's attacking play that saw them to an easy victory as Belgian playmaker Kevin de Bruyne set up three goals.
After Otamendi's second-half opener, De Bruyne flicked a deft pass through for Sterling, before picking out Stones for his goal, and then linking with Spanish teenager Diaz, who scored with a superb strike.
"It is not easy to find a player like him anywhere in the world," said Guardiola of De Bruyne. "Hopefully he can be stable in his mood. When his mood is positive, he can do whatever he wants."
Madrid pulled one back with the last effort of the game - a stunning goal from Oscar Rodriguez - but City were dominant.
"If we play with this intensity, we can compete with everyone. That is our dream," added Guardiola, who confirmed playmaker David Silva will be fit for the Premier League opener at Brighton on 12 August.
'Losing to Barca was important'
Manchester United ended their pre-season tour of the United States with defeat by Barcelona - a game that manager Jose Mourinho said "was important to lose".
Neymar, who has been linked heavily with a move to Paris St-Germain, scored the only goal of the International Champions Cup contest in Washington to consign United to their first pre-season defeat.
The French club have reportedly met the Brazilian's 222m euro (£199m) release clause but the 25-year-old played 45 minutes, capitalising on a mistake by Antonio Valencia to score in the 31st minute.
Barcelona would have been out of sight in the first half but for a string of fine saves from United goalkeeper David de Gea.
"I think it would be very bad for us to leave the US without a defeat," said Mourinho. "Playing against teams like Real Madrid, Barcelona, Manchester City - it would be very bad to go home with just victories."
Manchester United now face Norwegian side Valerenga on Sunday before playing Italians Sampdoria in their final pre-season match in Dublin on Wednesday.
They meet Real Madrid in the Uefa Super Cup on 8 August.