LeBron also aggravated an ankle sprain when he landed awkwardly on an official's foot.
"It's not feeling too well right now," LeBron told reporters after the game. "I don't know what happened in the first half. I played [much of] the second half and overtime, and strained my groin. I'll see how I feel on our trip to Portland tonight and into tomorrow. But it ain't feeling too good right now."
LeBron played through the injuries on Friday, scoring 11 of the Heat's final 19 points. In the overtime loss, he had 33 points and eight assists in 44 minutes.
According to ESPN.com, LeBron is currently a "close call" to play tonight against the Blazers and will likely test it out pregame to decide.