With the A-League season beginning on Monday, just how important is round one?

Amid a coronavirus outbreak in New South Wales, the opening round has been rejigged, with Western United to host Adelaide United in the first game of the season.

Brisbane Roar host Melbourne City on Tuesday before the Western Sydney Wanderers take on Macarthur and the Central Coast Mariners face the Newcastle Jets in the F3 Derby on New Year's Eve.

The opening round would seem like just another game, but history shows otherwise.

With the help of Opta data, we assess just what round one means in the A-League.

Opening loss and trophies become difficult

Incredibly, only twice in A-League history has a team that lost in round one gone on to be crowned champions or premiers of that season.

The first instance came in 2011-12, when the Mariners were edged by Brisbane in round one, but went on to win the Premiers' Plate, finishing two points clear of the Roar.

Melbourne Victory were the second, going on to be crowned champions in 2017-18 despite a 1-0 loss to Sydney FC in round one.

In all, six of the nine teams to do the A-League double of being crowned premiers and champions in a single season have done so far after winning in round one. The other three drew. Of the 15 champions, seven have won and seven have drawn, to go with Victory's 2017-18 defeat, in round one. Nine of the 15 premiers have won in the first round, alongside five draws and the Mariners' loss.

Round one looks hugely important in the A-League.

Fast-starting Sydney, Glory woes

Sydney have scored more goals (21) in round one games than any other team in the competition, while earning the most points per game (1.7) of teams to have featured in at least five seasons.

The Sky Blues have lost just two round one matches in their history, and the most recent of those was in 2012-13. Their first outing of the 2020-21 season will be against Wellington Phoenix on January 2.

On the other hand, Perth Glory have lost more games in round one than any other team in A-League history with seven.

In contrast to Sydney, Perth are winless in their past five openers, their last win coming in 2014-15.