Serena Williams is set to play her first tennis match since her daughter's birth.
Some well-placed U.S. media commentators have expressed doubt that Williams will play the Australian Open even since her announcement she would play the exhibition in Abu Dhabi.
Williams and Ostapenko will be the first women ever to participate in the Mubadala World Tennis Championship which was previously contested by only male players, who warmed up there ahead of the season-opening Australian Open.
Any doubt that Serena Williams would be back in time for the start of the 2018 tennis season was all but erased on Sunday morning, when the 23-time Grand Slam champion essentially delivered an early Christmas present for her fans.
It is the first time a women's tennis match will be staged at the Abu Dhabi showpiece.
"Last season was really incredible for me and I can not wait to continue the start of my new season at such an unbelievable event".
Serena Williams will return to competitive tennis next week after almost one year off the court.
The Latvian said: "It is a huge honour to be part of that history". Should everything be confirmed, Williams will feature on the final day's action.
The trio have been replaced by Roberto Bautista-Agut, Kevin Anderson and Andrey Rublev, and they join former world No 1 and 12-time grand slam victor Novak Djokovic, as well as Pablo Carreno Busta and Dominic Thiem.