James, who had quietly been dealing with tightness in his lower back since the season started, aggravated the soreness when he dove for a loose ball in the first half of Thursday's 102-97 win against the Los Angeles Clippers.
Heat coach Erik Spoelstra said Friday the team is taking a cautious approach with James, who has spent much of Thursday and Friday morning receiving treatment. James will be evaluated before Saturday's game against the Boston Celtics.
"It's stiff, it hurts," James said after the Heat's practice at AmericanAirlines Arena. "I'll get more treatment today and see what happens. I plan on playing [Saturday]. If it gets worse, it would make more sense for me to sit out."
James was visibly limited during Thursday's game and spent time on the bench with a heating pad or along the baseline being stretched by team trainers. But James finished with 18 points, six assists and five rebounds in 37 minutes. He also had four fouls and four turnovers.
James hadn't specifically mentioned his back issues before Thursday's game, but he has talked since training camp about his conditioning not being where he needed it to be entering the season. Part of the reason was that James took a break from his normal offseason training to get married and travel extensively in the weeks leading into camp.
Spoelstra said the Heat are at a point in the season where James could take a break if needed until the pain subsides.
"We just have to see how he feels tomorrow," Spoelstra said. "He's been able to play and compete. Guys go through various things during the course of the season. At least right now, thankfully, it's not something worse. He's like any other player. During an 82-game season, even the strongest and fittest will go through something."
James said he's been dealing with back problems early in the season since his third year in the league. At times in the past, he's had to sit out the second half of games, but on Friday couldn't recall missing an entire game because of tightness in his back.
The discomfort varies and affects his game in different ways.
On Tuesday, James played through the ailment and had his best game of the season with 35 points, eight assists and eight rebounds against Toronto. He didn't play with the same aggressiveness Thursday.
Overall, James' production hasn't taken much of a hit. He's averaging 24.3 points, 7.7 assists and 5.5 rebounds in 37.5 minutes through six games.
"LeBron James' back has been sore for a while, but he's still on pace -- LeBron James pace," Heat guard Dwyane Wade said. "His back was sore in Toronto, and he still had 35."
James said there's no structural damage to his back but there's nothing more he can do until the pain subsides.
"I've had back issues before, so I kind of know how to tackle it," James said. "But I'm not where I want to be physically. I don't like to rest. I've never been able to rest through anything. It's something I'm probably going to continue to play through it, do the exercises and the treatment until I get better. Hopefully it can turn around."