Miami Heat guard Kyle Lowry will miss the start of the team's Eastern Conference semi-final series against the Philadelphia 76ers as he continues to battle a hamstring injury.

The 36-year-old has been on the sidelines since suffering the injury during game three of the quarter-final series win over the Atlanta Hawks on April 22, as the Heat chase a first NBA championship since 2012-13.

Lowry was listed as an absence for Monday's game one in a social media update from the Heat, and though coach Erik Spoelstra says the six-time NBA all star is making good progress in his recovery, he remains unsure as to when he will return.

"I'm not even going [on] any kind of timetable," Spoelstra said after Sunday's practice. "I know he's doing more. Gym has been great. Everybody's been able to do something and to prepare for the series."

Lowry claimed his one NBA championship to date with the Toronto Raptors in 2019, and has impressed for the top-seeded Heat since joining the franchise last year.

Meanwhile, the team listed Jimmy Butler as questionable after he sat out the final game of their series win over the Hawks with a knee injury, although the 32-year-old said he was confident he would be ready to return to face the Sixers after Saturday's practice.

"We've had so many different rotations and line-ups during the course of the year that we've been forced to stay in the present moment," he added.

"And we have great care and empathy for the guys that have missed time, but we just have to totally lock into who's available. Everybody else is ready to go, and we have a big challenge.

"This is a series that could potentially change, both sides, three or four times. It could feel totally different by the middle of it, so that's why you can exhaust yourself with all the different hypotheticals. 

"We basically know, both teams, who's going to play game one, and that's the way it should be. You shouldn't be thinking about game two, game three, game four, anything past that. Just embrace the competition and what's ahead."

The Heat also have doubts over Markieff Morris, Caleb Martin, Max Strus, P. J. Tucker, and Tyler Herro ahead of their semi-final series.