Jose Mourinho refused to say whether he thinks his Manchester United squad are strong enough to compete for the Premier League title next season.
United have brought in three players for about £68m this summer, and the 55-year-old told ESPN he would like to sign “two more players”.
Asked at a news conference if he was confident of challenging, Mourinho said: “I don’t answer your question.”
The Portuguese stayed silent when pressed to explain why.
United were runners-up to Manchester City last season, finishing 19 points behind the champions, and lost to Chelsea in the FA Cup final.
The £47m spent on midfielder Fred has been their biggest outlay of the summer.
The club have also been linked with Chelsea’s Brazilian midfielder Willian, Eintracht Frankfurt’s Croatia winger Ante Rebic and Tottenham’s Belgian defender Toby Alderweireld.
Mourinho was speaking to the media in Los Angeles before his side’s pre-season friendly against AC Milan on Thursday.
The United boss said he was not fully satisfied on the USA tour because he was without several members of his first-team squad, who are on a break following the World Cup.
The Red Devils had 12 players competing at the tournament, with eight featuring in the semi-finals. Tottenham also had 12 players in Russia while Manchester City had 16.
“I don’t have the majority of the players that are going to be in the squad on 9 August when the market [transfer window] closes and we can make it official for the season. So of course I’m not happy, to have just a few players,” he added.