At 45-years-old Ebba Hay was the oldest tennis player at the Stockholm Olympics, and was the oldest female competing in 1912 in any sport. She played only the indoor mixed doubles event, partnering Frans Möller, and they lost their first round match. Hay competed in the Swedish Covered Courts Championship in 1904, losing in the quarters, and 1906, losing the final to Martha Adlerstråhle. Hay was ranked in the Swedish top three from 1907-13. In 1912, she was well thought of enough to be on the Committee for the Lawn Tennis at the Stockholm Olympics. Technically, she represented Kungliga Lawn Tennis Klubben (KLTK) at the 1912 Olympics, as that club entered all the Swedish tennis players, but Hay actually played out of the Jönköping Lawn Tennis Klubben.