World sport continued to reel from the surge in COVID-19 cases on Friday, as a number of competitions are postponed, including the Premier League in the UK and the National Football League in the U.S.

As Europe's top soccer leagues prepare to wind down for a short winter break, England's Premier League is looking to go full steam ahead over the busy festive period. Nine scheduled matches have been postponed so far due to COVID-19 outbreaks. 

Only half of the weekend's games will go ahead even as many managers sought clarity on what the threshold for postponing games was and questioned whether the integrity of the competition was at stake with so many players missing. 

The Premier League finds itself in a precarious situation due to COVID-19 outbreaks, Newcastle United boss Eddie Howe said. 

"I think it's probably on a knife edge would be my verdict on it. I think when you start losing players to COVID-19, then the worry for me is that the competition becomes slightly unfair. I don't think anyone wants to see that," Howe said. 

The Premier League only grants a postponement if a club has fewer than 14 players available, with the board examining requests on a case-by-case basis. 

Title contenders Chelsea and Liverpool had key players missing on Thursday, while Manchester City boss Pep Guardiola cancelled his news conference on Friday after returning a COVID test. 

Tottenham Hotspur, who had 13 cases among players and staff, have had three matches in all competitions postponed and manager Antonio Conte warned the workload and fixture congestion for players who have just recovered from COVID could be detrimental. 

"You can't give them the same charge of work as other players... If you want everything very soon, you risk injuries," Conte said as Spurs return to action on Sunday, when they host Liverpool, for the first time since Dec 5. 

Meanwhile, the National Football League (NFL) has reportedly postponed games for the first time all season due to COVID-19 outbreaks that required three upcoming contests to be rescheduled from the weekend to early next week. 

The Cleveland Browns, who were set to face the Las Vegas Raiders in a Week 15 encounter on Saturday, will now host the game on Monday, the NFL said in a news release. 

The Seattle Seahawks-Los Angeles Rams and Washington Football Team-Philadelphia Eagles games that were originally scheduled to be played on Sunday will now go ahead on Tuesday. 

(With input from agencies)