"I was not on top of my game and that was the result everybody saw", said Thiem who has lost in straight sets in both French semifinal matches.
But the Brit remained philosophical in the wake of another semi-final exit at Roland Garros.
Mattek-Sands and Safarova won the French Open in 2015.
Murray, the finalist from previous year in Paris, re-grouped himself. It was Pilic who inspired the creation of the Association of Tennis Professionals, incidentally, and who would briefly mentor Novak Djokovic.
Rafa got another early break and behind a serve that became nearly untouchable at times, cruised to a two-set lead.
The boys' final will be between Nicola Kuhn of Spain and Australian Alexei Popyrin.
The pair had already been on court for three hours. When Wawrinka finds his rhythm and is spraying winners left and right, he's proven to be one of the tougher players on tour to beat.
1973 - The last time a man older than the 32-year-old Wawrinka appeared in the men's final at the French Open.
Wawrinka was on the court more than twice as long as Nadal by prevailing in a four-hour, 34-minute marathon.
Murray's serve quickly came under pressure in the second set, saving a break point in a nine-minute game to hold for a 3-2 lead.
Murray endured a disappointing claycourt season leading into Roland Garros - suffering early defeats in Madrid and Rome - but rediscovered his verve in Paris where his run included victories over Juan Martin del Potro and Kei Nishikori. However, his hot streak wore off in the face of Murray's tireless defense and he found a 3-0 lead turned into a 5-7 loss.
Warriors One Win Away From Capturing NBA Title
Golden State actually appeared to be in a bit of jeopardy on Wednesday night in Game 3 , trailing by 113-107 late in the contest. Tristan Thompson finished the game with ZERO points and - even more alarming - only three rebounds in 23 minutes of play.
Murray admitted that Wawrinka was the better player.
There were five breaks of serve in the 12 games. Years ago, he would have been in a deep funk.
Nadal certainly won't be taking Wawrinka lightly Sunday, though: He is a ideal 3-0 in grand slam finals, memorably topping the left-hander to open his account in Melbourne in 2014.
The same symbols are also displayed on the inside frame of his racket.
Stan Wawrinka and Rafael Nadal meet Sunday in the 2017 French Open Final.
Wawrinka's fitness proved the difference as the 32-year-old from Switzerland dominated a worn out Murray in the final set at Paris.
- The Swiss produced a tally of 18 winners to Murray's 11 in a hard-fought fourth set.
"I lost a little bit of speed on my serve which wasn't allowing me to dictate many points on my own serve", explained Murray as Wawrinka went into overdrive to record a 10th successive win on clay.
The quality of the tennis for the first four sets was sublime - there was no possibility of boredom as there was no predicting what the players might produce next.
"It was mentally a tough battle today, especially in five sets", Wawrinka said.
As if played out, Stan squandered a chance to serve out the first and Murray made him pay.
The first set alone had enough drama for a whole match. Nadal will capture his 10th championship at Roland Garros.
Nadal can become only the third man in history to make 10 appearances in the final at one Grand Slam tournament.
Wawrinka, Nadal and Thiem have won every set so far.
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