Philadelphia 76ers head coach Doc Rivers said he is "very concerned" if the NBA can complete a bubble-free season amid the coronavirus pandemic.

The 2020-21 campaign is scheduled to begin on December 22 in a non-bubble environment after last season concluded at Walt Disney World Resort.

COVID-19 forced the 2019-20 season to be suspended in March before the league resumed inside the Orlando bubble in July, with the Los Angeles Lakers going on to win the championship in October.

As the NBA prepares for a reduced 72-game regular season, new 76ers coach Rivers addressed his concerns by pointing to the NFL and college sport.

"Man, I tell you I'm very concerned if we can pull this off," Rivers, who replaced Brett Brown after leaving the Los Angeles Clippers, told reporters on Tuesday.

"Just watching football, in college you have Ohio State missing games, Pittsburgh and Baltimore can't even play a game [in the NFL], they can't get to it, hopefully they play Wednesday now.

"The difference in football is they play once a week. They have 1,000 players, so when you miss three or four players, you can still get away with it. If we miss three or four players, we're in trouble, especially with the amount of games [we play].

"We're playing three to four games a week. So if one of our guys, or two of our key guys, get the virus and they miss 10 days to 14 days, that can be eight games. In a 72-game season, that can knock you out of the playoffs.

"That's a concern, our guys' health is a concern, and that's tough. As a coach, you want to go into your chief concerns being more basketball, and I think every coach's concern right now is probably non-basketball."

Former Boston Celtics coach Rivers is just a few wins away from joining an esteemed group of coaches.

He has 1,034 career wins (770 losses) across the regular season and playoffs – just three victories shy of entering the top 10 for all-time wins in the NBA, level with Red Auerbach. Current San Antonio Spurs great Gregg Popovich tops the list with 1,447.

If you are just looking at the regular season, Rivers has overseen 943 wins (681 defeats), one behind 10th-placed Bill Fitch. Former Milwaukee Bucks, Golden State Warriors, New York Knicks and Dallas Mavericks coach Don Nelson – a three-time championship-winning coach – stands alone at the top with 1,335.

Rivers also oversaw the fifth-best record in the NBA with the Clippers – 356-208 in the regular season – but failed to reach the Finals.

The Clippers also top the list for most consecutive seasons with 40-plus wins on nine – seven of those campaigns were on Rivers' watch.

Rivers has a 66.2 winning percentage in his first four seasons with a team, only behind Steve Kerr (80.8), Avery Johnson (73.5), Mike D'Antoni (68.2) and Stan Van Gundy (67.7).

"Taking a job during this year of COVID is brutal," Rivers, whose 76ers will open their preseason against the Celtics on December 15, said. "I will just say that. It's brutal. And then making the changes, because we haven't had a chance to be in the gyms with our guys. We can't even put in our stuff, and then you have like a week-and-a-half, and you're in [regular-season] action.

"We're going to simplify things as much as possible. It clearly wouldn't be what I would do if it was normal circumstances. It is what it is. Teams like Boston and Milwaukee and Miami, that are already set, they have an advantage.

"We are fine with that, but we have to make up the deficit, and we probably have to do it through work."