The Milwaukee Bucks are struggling to sustain their performance levels over a full game amid their five-game losing streak, says coach Doc Rivers.

The Bucks have failed to win since triumphing in their season opener against the Philadelphia 76ers, going down 114-113 to the perfect Cleveland Cavaliers on Saturday.

They raced into a 38-30 first-quarter lead at Fiserv Forum before tailing off badly, prompting Rivers to question their fitness.

“We don’t sustain the game,” Rivers said. “We haven’t been able to sustain 48 minutes.

“We’ve got to figure that out. That’s on us. We have not found the correct rotation yet.”

Damian Lillard was unfortunate to be on the losing team after scoring 41 points with nine assists and shooting 10 of 15 from 3-point range, and he pointed out that several opponents had benefitted from having strong bench options against them.

“I think every team that’s hurt us, they’ve had somebody come in off the bench and have an impact on the game,” Lillard said. 

“They had a guy come in and knock down three 3s when they were bleeding and we had them down and our energy was right. He comes in and, ‘Bang, bang, bang.’"

However, Giannis Antetokounmpo – who had 34 points, 16 rebounds and nine assists – believes the Bucks’ results will soon turn, claiming their displays have improved.

“It doesn’t mean we’re going to go to a five-game winning streak or a 10-game winning streak,” Antetokounmpo said. 

“But I know that we’re playing better. We trust one another better. The ball is moving. There’s a lot of good things that we can do. That’s all we can control.”