A 109-98 victory on Monday night saw Miami complete a 4-0 series win over the Charlotte Bobcats, and James believes that it is encouraging they have continued to improve throughout the first round.
"We got tested by a young, scrappy Bobcats team," the four-time MVP told reporters. "We responded with a championship-type attitude.
"We improved every game and that's the most important thing about this series."
Miami will face either the Brooklyn Nets or the Toronto Raptors in the second round.