The queen intends to hand over her All England Lawn Tennis & Croquet Club patronage to Kate Middleton, according to the Sunday Times.
The club, where she has been patron for 64 years, hosts the Wimbledon championships every year among other events.
Her grandson, Prince Harry, will replace the British monarch as patron of the Rugby Football Union (RFU), the governing body of rugby union in England.
The Queen is understood to be assessing how much time she can now devote to the 628 organisations and charities to which she is affiliated, the daily reported.
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Aides have described her 90th birthday in April as a "game changer" and talks have reportedly been held at Buckingham Palace to see whether other patronages could be given to various members of the royal family.
It is thought that Prince William, the Duke of Cambridge, who is already president of the Football Association, could also take over the role of patron from his grandmother.
Her son Prince Charles and grandson Prince William are expected to give speeches and pay personal tributes to the monarch. Several other public events are being staged to mark the Queen's 90th birthday.
In May, a horse pageant celebrating her life will be held over four days from May 12 in the grounds of Windsor Castle. More than 900 horses and 1,500 performers from around the world, including actors, dancers and musicians, will take part in the 90-minute show, which will be broadcast on TV. The Queen will attend the final show on May 15.
The Queen's birthday parade, Trooping the Colour, will take place at Horse Guards Parade the following day with officials understood to be discussing plans to include a special salute.
The weekend will conclude with the Patron's Lunch on June 12, a massive street party on the Mall in central London.