Super League clubs will play 25 matches in the regular season in 2021, two fewer than originally planned.
The change is a result of the decision to push the start of the season back by a fortnight to Friday, March 26, when Super League will begin with a double-header behind closed doors at Headingley.
The opening game will be a repeat of the 2019 Grand Final, with reigning champions St Helens facing last year's Challenge Cup finalists Salford, and will be followed by a clash between runners-up Wigan and newly-promoted Leigh.
A competition fixtures working group considered a range of options, from playing 22 rounds to 27, and in the end recommended the ditching of two of four loop matches which was approved by the Super League board.
There will be two other double-headers on the opening weekend, also at Leeds, with all six games to be shown live on Sky Sports.
On Saturday, March 27, Wakefield will play Leeds and Catalans Dragons take on Hull KR, while the following day, Hull play Huddersfield and Castleford take on Warrington.
The Dacia Magic Weekend, scrapped in 2020 due to the coronavirus pandemic, remains part of the calendar for 2021 but due to ongoing crowd restrictions at sporting events, the proposed date for the St James' Park showpiece has been moved from the end of May to the first weekend in September.
Fixture planners were constrained by a fixed Grand Final date of October 9, with the World Cup due to start just two weeks later.
The full fixture list, due to be published on Friday, February 26, will be weighted to ensure that the more attractive games, including derbies, will be played later in the year in the hope they could be held in front of crowds.
Super League chief commercial officer Rhodri Jones said: "With the start of the season a little over a month away, Super League would like to thank all our clubs, Sky Sports, our partners and the RFL for their tireless work in helping us make these announcements today.
"We look forward to continuing to work together throughout the 2021 season to deliver what promises to be another fantastic season.
"Confirmation that Dacia Magic Weekend remains an important part of the 2021 season shows our commitment to the event and thanks must go to Newcastle United in supporting us to achieve this.
"Whilst it is frustrating for all involved to not be welcoming fans back into our stadiums for the start of the season, we are hopeful that as the situation in the country continues to improve and the vaccine rollout nears completion, we will be seeing fans enjoying live sport again soon.
"We will continue to work with all of our stakeholders to ensure that we are ready to deliver the return of fans in a safe and secure way."