The opening fixture was due to be held at Nationals Park yesterday only to be called off with "ongoing contact tracing involving members of the Nationals organisation" cited as the reason for the decision.

Two subsequent games have also been postponed.

One player tested positive for COVID-19 on Wednesday (March 31) before two more were found to have contracted the virus following additional testing on the eve of the match.

Nationals general member Mike Rizzo said a fourth player was considered a "likely positive".

Those infected have been placed in quarantine along with close contacts while the team continues to conduct contact tracing.

"We don’t want this thing to spread any further," said Rizzo.

"We want to make sure that everybody’s healthy."

Rizzo said one of the players that tested positive had a fever while the others were asymptomatic.

"I've got the utmost confidence that it was not a player breaking protocol," added Rizzo.

"We were very diligent throughout the whole spring training.

"The day we landed in D.C. was the day we got our first positive.

"It's only conjecture on what happened and when it happened, and we don't want to get into that."

MLB’s health and safety protocol includes a 10-day quarantine period for a positive case, and seven days for a close contact.

"It’s a shame that we can’t play today, but we need to stay positive," Nationals manager Dave Martinez said.

"I’ve talked to a lot of players, and my concern is about their health and safety."

Mets manager Luis Rojas, whose team had four games postponed because of COVID-19 last season added: "This game teaches us that there's just a lot of uncertainty.

"At the same time, what we've gone through since last year, I think that we're pretty open-minded that things like this can happen.

"Right now, our sympathies are with the team on the other side, with the Nationals, that things are contained and that everyone's safe."

The National Hockey League (NHL) has postponed the Vancouver Canucks’ next three games due to COVID-19 cases.

Forward Adam Gaudette, defenseman Travis Hamonic and a member of their coaching staff tested positive for coronavirus.

Tomorrow’s match at Edmonton Oilers as well as Canucks’ back-to-back meetings with Winnipeg Jets on Sunday (April 4) and Tuesday (April 6) have been postponed.

"Whether we have someone that gets it or not, everyone is trying their best to abide by the protocols," said Vancouver forward JT Miller.

"The timing is obviously not great - there's no good timing - but it doesn't change anything.

"No matter what the circumstances, no one wants to get it, no one wants to spread it, nothing changes."

There have been 50 games postponed since the NHL season began on January 13, including 45 because of COVID-19.

The other five were called off due to weather-related issues.