The Prince of Wales sent a rallying message of support to the British & Irish Lions rugby squad ahead of their history-making test match.
"Good luck to Andy and the whole @britishandirishlions squad as they kick off the 2025 Tour tonight against Argentina in Dublin. Lions Tours are always special - the history books await!," Prince William wrote in a personal social media message, signing off with his initial "W".
The royal is the patron of the Welsh Rugby Union, while the Princess of Wales is patron of the Rugby Football Union (RFU) and the Rugby Football League (RFL).
It will be the first match the Lions have played in Ireland and in another first, the players will have the names printed on the back of their shirts.
It comes ahead of the Lions' tour to Australia for six more matches and three tests against the Wallabies.
Special day
William turns 43 on Saturday 21 June and traditionally spends his birthday privately with wife, Kate, and their three children.
Last year, Kensington Palace released a fun family snap taken by the Princess, showing William, George, Charlotte and Louis holding hands as they jumped off a sand dune on a Norfolk beach.
"Happy birthday Papa, we all love you so much! Cx," Kate wrote in the accompanying caption.
The Princess was in the middle of her cancer treatment at the time, during a year which the Prince described as "brutal" for his family, with his father, King Charles, also diagnosed with the disease.
Kate completed her treatment last September and confirmed she is in remission in January.
The mother-of-three has been making a gradual return to her public duties amid her recovery.
She pulled out of attending Royal Ascot with her husband on Wednesday as she continues to find the right balance following her treatment.