A vastly expanded Big Bash League will be in direct competition with a Test for the first time in a sign of how tightly Cricket Australia has been forced to squeeze in the season in order to fit in a full home and away schedule.

The 2018 season will be 13 days longer than the previous edition. While the governing body is to officially launch the tournament on Wednesday, the full schedule was published on Tuesday evening by News Corp, owner of the new rights holders Fox Sports, which will show every match of the competition on its pay television service. The free-to-air network Channel Seven will air 43 of the 59 games stretching from December 19 to February 17. There will be pressure on all sides to get the tournament's audiences growing again.

As CA has moved towards expanding the BBL, there has been a small but notable downward trend in television viewership over the past three seasons on the Ten network. From a peak of audience interest in the 2015-16 summer, viewing audiences shrank by 6% in 2016-17, and by a further 10% in 2017-18. All this is according to OzTam's five-city metro average audience figures - the recognised television industry standard in Australia.

With the Perth Scorchers and the Adelaide Strikers proving to be dominant forces over the past two seasons and the Hobart Hurricanes also performing strongly, there will be some eagerness for the major-market Melbourne and Sydney teams to perform at a higher level and thus drive audiences in Australia's two largest cities.

Whether the audience will grow or be further diluted by its simulcast across both Seven and Fox Sports is one of many questions to be posed this summer. Either way, the BBL will remain CA's primary vehicle to attract new audiences to the game, with the new AUD 1.18 billion broadcast rights deal providing fresh money to sell it with. The flurry of new matches has created a fresh set of scheduling headaches.

According to the schedule, the Melbourne Stars versus Brisbane Heat fixture at the MCG will begin at 7.40pm on January 27, day four of the day-night Test between Australia and Sri Lanka at the Gabba. The final session is scheduled to run from 7pm to 9pm Eastern Time, with a possible finish as late as 9.30pm to make up for lost time. Seven and Fox Sports are listed to be broadcasting both matches.

Never before in the seven-year history of the BBL has a match been set to clash directly with a scheduled session of a Test. In previous years, Melbourne and Sydney Tests played during the day have commonly been followed by BBL matches at night, occasionally in the same city. However, CA had always managed to avoid forcing fans to choose between matches.

Though the second and third days of the Gabba Test do not have BBL matches taking place, day one of the match, January 24, will be immediately followed by a match starting at 9.40pm Eastern Time, between the Perth Scorchers and the Sydney Thunder at the Perth Stadium. Another is scheduled for 9.15pm Eastern Time, also in Perth, between the Scorchers and Melbourne Renegades on January 28, the final day of the Test.

These matches count among those described by the Seven chief executive Tim Worner as part of "mega days" on the network, which has taken over free-to-air rights for the first time after Nine held them for the previous 40 years, dating back to Kerry Packer's World Series Cricket breakaway in 1977.

"There are going to be 13 mega-days starting with cricket in the morning, going to Seven News, and continuing cricket into the night," Worner, who hired the former Ten executive Dave Barham to helm the network's cricket coverage, told the Australian Financial Review. "That 30 seconds between overs, in a T20, no one is going anywhere, it's a very high-engagement commercial break we can offer our customers and there's a lot of that.

"We're a storytelling organisation. The most valuable 30 seconds in Australian marketing is part of our cricket coverage. We don't go into these things without a plan, and we have a plan to monetise the sport. Cricket is a big part of the Australian psyche, and so's AFL. Now Seven has cricket and AFL, those two things are going to help define our brand."

Other notable tournament fixtures include a tournament opener between Brisbane Heat and the 2018 winners Adelaide Strikers at the Gabba on December 19, three games on the Gold Coast, including a neutral fixture between the Melbourne Stars and Sydney Thunder on January 5. Further to hopes of better tidings from Melbourne and Sydney, the Stars and Renegades will play a New Year's Day match at the MCG, while the Thunder and Sydney Sixers will meet on Christmas Eve.

To accommodate the extra matches, there will be six double-header days and one triple-header on January 13. The semi-finals will be played on February 14 and 15, with the final to be played in mid-Sunday afternoon on February 17, amounting to a total of 12 games in February, following the conclusion of school holidays.