As the NBA tightened coronavirus protocols to try to preserve a season teetering amid positive tests, thinning rosters and game postponements, the league made a dramatic change that most franchises had wanted all along: the closing off of rooms to non-team guests in road hotels.

The NBA and National Basketball Players Association on Tuesday reached agreement on several more revisions to policy, including the league further limiting movement for players and staffs on road trips. The league is no longer allowing players and staff to leave hotels for non-team activities, and it is eliminating visitors to hotel rooms, which one GM had told ESPN had been "the Mack truck driving through all our protocols."

Players were previously allowed to have up to two guests in hotel rooms, including those who were family members and long-standing personal friends.

The NBA has had to postpone four games this week, including three involving the Boston Celtics, who are unable to muster eight eligible players because of COVID-19 issues. Boston, Miami, Philadelphia, Dallas, Washington and Chicago are among teams who have had significant losses of active players due to positive tests and contact tracing.

Beyond the changes involving guests on the road, the two sides agreed to several other things to tighten the protocols amid several teams having large clusters of players either testing positive for COVID-19 or being caught up in contact tracing as a result of those positive tests.

Until at least Jan. 26, when teams are in their home markets, both players and staff must remain at home unless they are going to a team-related activity, exercising outside, performing essential activities or "as a result of extraordinary circumstances."

They also are supposed to limit away-from-work interactions to family, household members and personal staff working in their home.

Anyone who regularly visits the home of a player or staff member must have two COVID-19 tests per week. Meanwhile, teams that have either players who tested positive or a high-risk staff member may require players and team staff to undergo five consecutive days of twice-a-day lab-based testing, in addition to daily point-of-care tests.

Also until at least Jan. 26, pregame meetings in the locker room can last no more than 10 minutes. Every other meeting involving players and staff must happen either on the court, in a league-approved space, or in an arena in a room big enough for everyone involved to be at least 6 feet apart. Everyone at these meetings must wear masks at all times.

Players are now not allowed to arrive at the arena more than three hours before tip on game days. Meanwhile, pregame and postgame interactions with players must be limited to elbow or fist bumps, extended socializing should be avoided and 6 feet of distance should be maintained as much as possible.

On team flights, teams now must structure their seating charts on planes to mimic their seating charts for the benches during games, while all treatment sessions at hotels -- including massages and physical therapy -- need to occur in large, open spaces and with 12 feet between stations. These interactions also require both masks and face shields.

Players now also must wear masks on the bench at all times. There will be a cool-down period when a player checks out of a game, with a designated area where they don't immediately need to wear a mask. However, once a player has done so, they have to go back to their seat and wear a mask until they are put back into the game.

They must also now always wear masks in the locker room, when doing strength and conditioning and when traveling with anyone who isn't a household member.

Coaches and staff continue to have to always wear masks during games.