Five-time major winner and former world number one Sharapova, 32, has been carrying a shoulder injury and hasn’t played since a first-round exit at the US Open.
With the world 137 out of Luxembourg, and turning her attentions to the 2020 season, 15-year-old Gauff moves into the main draw for the event which starts next Monday.
Gauff, who electrified Wimbledon by coming through qualifying on her way to the last-16 in July and then made the third round at the US Open, reached her maiden WTA quarter-final in Linz in Austria on Wednesday, assuring herself of a place in the world top 100 for the first time.
Also out of Luxembourg is Germany’s world number 13 Angelique Kerber who has a leg injury and Danielle Collins, who has been diagnosed with Rheumatoid arthritis.
