0721 GMT July 17, 2018
But the four-time NBA Most Valuable Player, trying to reach his eighth consecutive NBA Finals, admited the Cavaliers need to make some changes before the best-of-seven playoff series resumes tonight in Boston, AFP reported.
"I have zero level of concern at this stage," James said. "You get better throughout the series. I've been down 0-1. I've been down 0-2. I've been down before. We have another opportunity to be better Tuesday.
"Game one has always been a feel-out game for me. I got a sense of how they are going to play me and I can make some changes going into game two. We'll see ways we can be better and get our offense into a better rhythm."
Jaylen Brown scored 23 points and grabbed eight rebounds while Al Horford added 20 points for the Celtics, who seized a 36-18 lead after the first quarter and never looked back, inflicting the second-worst game one playoff loss James has ever suffered.
Marcus Morris had 18 points and 11 rebounds for Boston and led a swarming defensive effort that shut down Cavs playmaker James, who averaged 34 points, 9.4 rebounds and 9.0 assists in prior playoff games.
"We just have to make it hard for him," Celtics coach Brad Stevens said. "Our guys played with good aggression."
James finished with 15 points on 5-of-16 shooting with seven rebounds and nine assists. He blocked two shots but also made seven turnovers as the Cavaliers missed their first 14 three-point attempts and came no closer than 14 points in the second half.
"They had a great game plan in game one," James said. "They did a great job of communicating the whole game. We have a lot of film to look at how they were making us uncomfortable. I was out of my rhythm the whole game."
The Celtics forced James to work harder defensively as well.
"They showed two bodies (against James) all night," Cavaliers coach Tyronn Lue said.
"When he thought he had driving lanes, they made him kick it out to other shooters.
"We didn't play well. We know we have to play better. They attacked us early on. We had some great shots we couldn't make and it snowballed from there."
Kevin Love led Cleveland with 17 points and added eight rebounds. Tristan Thompson had a game-high 11 rebounds off the Cavs' bench. Jayson Tatum added 16 for Boston and Terry Rozier had eight points and seven assists.