Boxing, much like tennis, is a uniquely solitary sport, and so when the news broke that American boxing legend Muhammad Ali had passed away at the age of 74, tennis players were quick to take to Twitter to show their respect and condolences.

Here’s what the WTA players and legends had to say as they mourned the passing of Ali, one of the world’s greatest athletes.

The true GOAT. What a sad day for everyone to loose someone so great and kind and someone who… https://t.co/OIyNfGPuTs

— Serena Williams (@serenawilliams) June 4, 2016

RIP Muhammad Ali ?? greatest sportsman ever .. You will be missed ..

— Sania Mirza (@MirzaSania) June 4, 2016

An inspiration. A legend. Forever a champion. RIP Muhammad Ali. ? pic.twitter.com/2TAlKmAOM8

— Caroline Wozniacki (@CaroWozniacki) June 4, 2016

Thank you for inspiration, motivation & legendary quotes. RIP #MuhammadAli you influenced so many great athletes! Never another like you!

— Shelby Rogers (@Shelby_Rogers_) June 4, 2016

Thinking of #MuhammadAli and remembering a man who was not afraid to take a stand and who was committed to being his authentic self.

— Billie Jean King (@BillieJeanKing) June 4, 2016

RIP Muhammad Ali…we will miss your spirit and humanity. You were shunned,excoriated and jailed for the same reason that made you a hero…

— Martina Navratilova (@Martina) June 4, 2016

'Don't count the days, make the days count' – RIP ?? #MuhammadAli

— Heather Watson (@HeatherWatson92) June 4, 2016

#MuhammadAli #TheGreatest #TheLegend. A Mark of Respect!

— Ana Ivanovic (@AnaIvanovic) June 4, 2016

#Legend #MuhammedAli #RestInPeace pic.twitter.com/pm9hWI6URq

— Sara Errani (@SaraErrani) June 4, 2016

Rest in Peace Legend ❤ float like a butterfly…. https://t.co/95JRDEfdIA

— Daria Gavrilova (@Daria_gav) June 4, 2016

Rest in peace, legend. #MuhammadAli pic.twitter.com/n0OOOHMIrF

— Nicole Gibbs (@Gibbsyyyy) June 4, 2016

Champions are made from sth they have deep inside them- a desire, a dream, a vision…But the will must be stronger than the skill #RIPChamp

— Kristina Mladenovic (@KikiMladenovic) June 4, 2016

Rip Muhammad Ali??The https://t.co/kzzeA7Uow1 in peace. pic.twitter.com/046DAk18J5

— Elena Vesnina (@EVesnina001) June 4, 2016

He is the greatest example! RIP … https://t.co/sKKVm2EPsI

— Svetlana Kuznetsova (@SvetlanaK27) June 4, 2016

Sad evening here in Phoenix as @MuhammadAli passed away. What a great man in and out of the ring, raised over $100million for charity!

— Bethanie MattekSands (@BMATTEK) June 4, 2016

Rest in peace, champ #MuhammadAli pic.twitter.com/OTdKteb7Bn

— Irina Falconi (@IrinaFalconi) June 4, 2016