The Warriors will carry that message into the regular-season opener against the Los Angeles Lakers on Wednesday night.
Golden State led by 11 early in the third quarter before the Blazers scored 22 straight points. The Warriors missed 17 shots in a row and were held scoreless for more than 8 minutes during Portland's run.
Stephen Curry had 17 points and six assists, and Klay Thompson scored 16 points for the Warriors, who blew a double-digit lead for the second straight game. Golden State lost 91-90 at Sacramento on Wednesday night after leading by 17 points in the third quarter.
"That's going to be our Achilles' heel. When we're not making shots, how do we defend? What's our personality going to be?" said new addition Andre Iguodala, who had nine points, four rebounds and two assists.
The Warriors ended the preseason 3-4, including wins against the Lakers in Beijing and Shanghai. Portland won its final five games to finish the preseason 5-2.