National Football League chiefs on Tuesday played down the possibility of completing the postseason in a "bubble" but admitted the league had not ruled out extending the regular season to make up for disruption caused by Covid-19.
In a conference call with reporters, NFL commissioner Roger Goodell again warned teams to strictly follow coronavirus safety protocols after last weekend's schedule saw games moved due to a cluster of cases affecting the Tennessee Titans and New England Patriots.
"We cannot grow complacent - not the players, not the coaches, not the rest of personnel," Goodell said. "90% is not good enough in this environment."
Goodell emphasised that the league would aim to be "flexible" over how it dealt with scheduling issues, but hoped to complete the season on schedule with the Super Bowl in Tampa, Florida, on February 7.
"If there was one consistent theme to our season it's flexibility and adapting," Goodell said. "Flexibility is going to be critical.
"We will have flexibility to be able to complete our season for the Super Bowl. That's the goal. We're all focused on that. And to do it safely."
The NFL's executive vice-president of operations Troy Vincent said the league schedule was "proceeding as is" and not planning a week 18.
NFL medical chief Allen Sills, meanwhile, said the league was leaning away from setting up a single-location "bubble" similar to the one deployed by the NBA to complete its season.
Sills said although the concept had been discussed, the league would prefer to avoid that option.
"We don't feel that is the safest course of action," Sills said. "I think we all have to recognize that there are no perfect solutions.
"First of all, a bubble is not going to keep out all infections. You still have other individuals that come in and out: service workers, security, other personnel. And we've known from other experiences that those individuals can be infected. So simply being in a bubble doesn't keep us safe.
"We still have to do all these measures of mitigation, with PPE, with identifications of symptoms, with testing, etc."
The NFL has taken a hard line on enforcing Covid-19 safety protocols since the start of the season, handing out more than $1 million in fines to teams and individuals so far. The league has also threatened to order games forfeited if safety protocol breaches lead to scheduling disruptions.
However, Goodell played down the threat of possible sanctions involving the Tennessee Titans, who have had 23 positive cases.
"We are really working closely in identifying and speaking to clubs and players and open dialogue," Goodell said.
"This is not about discipline. This is about making sure we're keeping our personnel safe and that's been our entire focus to date."