Princess Kate hits the tennis court with kids in first solo appearance since announcing pregnancy

Kate, 35, also met with some of the U.K.'s top junior tennis players.

— -- Princess Kate stepped out, in her first solo royal engagement since announcing her third pregnancy, to play tennis with a group of kids.

Kate, 35, who is due in April, stepped out in a track suit with her hair pulled back in a ponytail for the event at the National Tennis Centre at Roehampton.

Kate, an avid tennis player, took part in a coaching session alongside a group of kids from the Lawn Tennis Association’s "Tennis for Kids" campaign that will give free tennis lessons and rackets to more than 22,000 kids this year.

The mother of Prince George, 4, and Princess Charlotte, 2, revealed that George is starting get the tennis bug like his parents. Kate asked for advice on how to teach George the sport.

"With George just being four he wants to whack a ball, so she was asking what sort of stuff she should be doing," said Sam Richardson, a National Tennis Centre coach. "They will struggle at that age to hit a ball. She said he's interested in it, but more in whacking the ball."

Kate also met with young people taking part in the Coach Core apprenticeship program, a charity Prince William, Kate and Prince Harry actively endorse. The program, supported by the Royal Foundation, trains people between the ages of 16 and 24 to become coaches, mentors and role models in their local communities.

Kate became a patron of the Lawn Tennis Association in December, a role she took over from Queen Elizabeth II, who was patron for 64 years.

Kate also watched a demonstration by British wheelchair tennis champion Alfie Hewitt and met tennis pro Johanna Konta and some of the U.K.’s top junior tennis players.

The Duchess of Cambridge spoke about her love for tennis in a documentary that aired on the BBC in June. She described how watching Wimbledon matches made her hope that she too could be a tennis star.

“It inspires young people including myself,” she said. “Every time Wimbledon is on I am thinking, ‘Yes, I could do the same’ and get out the racket. Sadly, not the same results.”

Kate has a tennis court at the country home, Anmer Hall, she shares with Prince William and their children. William, also 35, and Kate are said to enjoy a fierce rivalry on the court.

Kate is gradually returning to public duties since announcing her pregnancy on Sept. 4. Kensington Palace revealed at the time Kate was suffering from hyperemesis gravidarum, or severe morning sickness.

Kensington Palace announced Monday that next week Kate will attend a benefit dinner for the Anna Freud National Centre for Children and Families, which she serves as royal patron.

Kate attended a Buckingham Palace reception on Oct. 10 to mark World Mental Health Day after taking time out of the public eye.

One week later, Kate made a surprise appearance with William and Prince Harry at a children's charity event in London where she danced with Paddington Bear.

She also joined William and Harry on Oct. 18 at the graduation ceremony of more than 150 Coach Core apprentices at London Stadium.