Former champions Venus Williams and Andy Murray were named in Wimbledon's initial list of wildcards on Wednesday for this month's grasscourt Grand Slam.
American Williams, who will turn 41 on Thursday, has won five out of her seven Grand Slam singles titles at Wimbledon but has slipped to 103rd in the women's world rankings.
She has not made it past the opening round at any tournament since reaching the second round of the Australian Open in February.
Britain's Murray won Wimbledon titles in 2013 and 2016 but is currently ranked 124th having endured a spate of injuries in the past few years.
Murray underwent hip resurfacing surgery in January 2019 and his comeback has also been complicated by niggling injuries which have limited his participation in tournaments.
The 34-year-old made an emotional return to playing on grass after three years on Monday when he defeated Frenchman Benoit Paire 6-3 6-2 at the Queen's Club championships.
Wimbledon cuts 2021 prize purse by 5%, tickets go on sale on Thursday
Prize money for this year's Wimbledon will be a little over 35 million pounds ($49.4 million), a 5.2% reduction from 2019 when the grasscourt Grand Slam was last held, organisers said on Wednesday.
Wimbledon was the only major to be cancelled in 2020 due to the COVID-19 pandemic and will this year return in its usual slot with the main draw starting on June 28.
The singles champions will bear the maximum hit to their earnings and will pocket 1.7 million pounds, down from the 2.35 million they were paid in 2019.
"As in previous years, and particularly in this challenging year for tour players, the focus of distribution has been on supporting players in the early rounds of the tournament," organisers All England Club said in a statement.
"Only four players (finalists and semi-finalists) in each singles draw will receive prize money at a lower level than was awarded in 2019."
Players participating in the qualifiers will see a 17.5% increase in overall prize money allocation while the wheelchair and quad wheelchair events will also get a 17% boost.
Organisers also confirmed that the men's and women's singles finals will be played with full crowds of 15,000 in attendance on Centre Court, making it the first outdoor sporting event in the United Kingdom to have full capacity since the start of the coronavirus pandemic last year.
Spectators have to register by Wednesday midnight to access the ticketing platform for the initial sale of tickets from 1 p.m. local time on Thursday, the organisers said. In previous years, the majority of tickets were allocated through a public ballot held months in advance of the tournament being staged.
The All England club added that 2021 ticket holders must wear face coverings at the venue grounds but will not be required to wear masks and maintain social distancing when seated at the venue.
They will be also need to present proof of COVID-19 status during entry, either in the form of both doses of vaccinations or a negative lateral flow test within 48 hours of attending.