"If you’re injured, you don’t play; if you play,…

“If you’re injured, you don’t play; if you play, you’re not injured” has been credited to Australian tennis coach Harry Hopman (1906-1985). It’s not known when he first said it. Tennis player Billie Jean King wrote in 1974:

“Now, among the Australians especially there’s a sort of unofficial code which says: If you’re injured, don’t play; and if you play, you’re not injured.”

The saying is now used in other sports besides tennis.

Wikipedia: Harry Hopman
Henry Christian “Harry” Hopman CBE (12 August 1906 – 27 December 1985) was a world-acclaimed Australian tennis player and coach.
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Davis Cup
Hopman was the successful captain-coach of 22 Australian Davis Cup teams from 1939 to 1967. With players such as Frank Sedgman, Ken McGregor, Lew Hoad, Ken Rosewall, Rod Laver, Neale Fraser, John Newcombe, Fred Stolle, Tony Roche, Roy Emerson, Ashley Cooper, Rex Hartwig, Mervyn Rose, and Mal Anderson, he won the cup an unmatched 16 times.

Google Books
Billie Jean
By Billie Jean King with Kim Chapin
New York, NY: Harper & Row
1974
Pg. 136:
Now, among the Australians especially there’s a sort of unofficial code which says: If you’re injured, don’t play; and if you play, you’re not injured.

Google Books
The Playboy Book of Tennis:
How to play winning tennis—and everything else you forgot to ask your pro
By George Soules and Peter Ross Range
New York, NY: Playboy Press
1982
Pg. 166:
“If you’re injured, don’t play; if you play, you’re not injured.” This tenet was observed by all.

4 June 1988, Boston (MA) Herald, “A painful ending for DJ” by Charles Pierce, pg. 74, col. 4:
He is of a mind with the father of Australian tennis, a man named Harry Hopman. One of Hopman’s first rules was that you never play with an injury. If you play, you are not injured.

SI.com (Sports Illustrated)
Posted: Tuesday January 11, 2011 10:08AM ; Updated: Tuesday January 11, 2011 12:09PM
INSIDE TENNIS
Bruce Jenkins
What we learned from Week 1
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Too bad Mr. Hopman wasn’t around for a comment (Harry Hopman, the legendary Australian coach, died in 1985). Never tolerant of excuses, Hopman often said, “If you’re injured, you don’t play. If you play, you’re not injured.”

Tennis Abides
January 16, 2012
We’re Not in Australia Anymore or Are We?
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Legendary Aussie Harry Hopman helped shape Jim Courier’s game and played a role in John McEnroe’s development as well. Hopman, among others, is credited for variations of this maxim, “If you are injured, you don’t play. If you play, you’re not injured.”

CBS—New York
Keidel: It’s Simple, Really — Knicks Lack The Winning Knack
By Jason Keidel
March 14, 2013 6:04 PM
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Remember the ancient axiom of pro sports. If you’re injured, you don’t play; if you play, you’re not injured. Of course, as with all earnest and honest maxims, that rule applies to all but the anointed Anthony, who has my beloved city so mesmerized that he literally does no wrong.