Maurizio Sarri urged Juventus to show less naivety on the ball after Adrian Rabiot's late lapse led to a 3-2 loss to Tottenham in Singapore.
The Serie A champions succumbed to defeat in Sarri's first match in charge courtesy of Harry Kane's sublime lob over Wojciech Szczesny from inside the centre circle in the third minute of added time.
New signing Rabiot dallied on the ball and invited a tackle from Lucas Moura, from which the ball spilled into Kane's path.
Gonzalo Higuain and Cristiano Ronaldo earlier scored to overturn Erik Lamela's first-half opener, before Lucas equalised in the 65th minute.
"It was a difficult game, there is a difference between us in our physical preparation," Sarri told reporters.
"Tottenham have players who have known each other for years and in the first half they seemed quicker, but it's normal.
"If we want to show our football we must defend further forward. In the first half we weren't high enough up the pitch, which made things difficult.
"In the second half we pressed better and we did some good things, even though we were naive with the lost balls.
"But I think this is also affected by the level of physical conditioning."
The International Champions Cup clash was the opening pre-season match for both clubs.
Debutant Rabiot said: "It was the first game, so there is still a lot of work to do. Physically I need to grow, but I felt good playing my first game.
"We are understanding each other very well within the team and with the coach."
Juve return to action against Serie A rivals Inter in China on Wednesday.