Roger Federer sent a classy message of congratulations to Australian Open champion Rafael Nadal after the Spaniard eclipsed the Grand Slam title record they shared with Novak Djokovic.
Nadal produced an awe-inspiring comeback in the trophy-decider on Sunday, recovering from losing the first two sets to beat Daniil Medvedev in a thriller.
The Melbourne match went on for almost five-and-a-half hours as the Spaniard refused to give up and gave his all to eventually secure a 2-6, 6-7, 6-4, 6-4, 7-5 victory.
The man from Mallorca's win was made even more incredible by the fact it comes just a few months after he was hinting at retirement as he recovered from a painful foot injury.
Federer, whose total of 20 Grand Slam titles was eclipsed as a result of Nadal's victory, jokingly referenced those talks of retirement as he congratulated his great rival.
"What a match!" he wrote in a public message on his Instagram story.
"To my friend and great rival @RafaelNadal. Heartfelt congratulations on becoming the first man to win 21 Grand Slam singles titles.
"A few months ago we were joking about both being on crutches. Amazing. Never underestimate a great champion.
"Your incredible work ethic, dedication and fighting spirit are an inspiration to me and countless others around the world.
"I am proud to share this era with you and honoured to play a role in pushing you to achieve more. As you have done for me in the past 18 years.
"I am sure you have more achievements ahead but for now enjoy this one!"
Nadal's victory was his 21st major singles titles, taking him one ahead of the previous record of 20 he shared with Federer and Djokovic.
Many might have expected it would come for the Spaniard at the French Open in the spring, as his dominance on clay courts is legendary and he has won 13 titles at Roland Garros.
By comparison, he had won the Australian Open only once in 2009 and had suffered defeat in four Melbourne finals since, making this success extra special.
Speaking on-court at the Rod Laver Arena after his win, Nadal was grateful to simply still be playing the game he loves.
"I don’t know what to say guys. For me it is just amazing. I did not know if I would be back on the tour playing tennis again," he admitted.
"You don’t know how much it means to be back here. You are amazing and thank you so much for all of your support.
"Without a doubt it is one of the most emotional [periods] of my career. To have the support I have received the last three weeks will stay in my heart. So many, many thanks."
He later added: "I thought this might be my last Australian Open but this has given me enough energy to maybe keep going. I will keep trying my very best to come again next year. Thank you."