- The Swiss hit 18 winners to draw level after two hours.
It was a repeat of last year's semi-final match, which the Briton won before going on to lose the final to Novak Djokovic.
Wawrinka, who was heading for his 10 straight win having defended his title in Geneva the week before stayed toe-to-toe with Murray in the second set before again becoming the first to claim a break over the Brit, breaking him again for the second set.
"I played pretty well these last few matches".
Only Wawrinka stands in his way this year, but the Swiss may just take some stopping.
Not that Murray was under-par, far from it.
"Sometimes a match changes after the first game in a set", said the 14-time grand slam victor. And I finished the year being World No. 1, winning here (in Paris), winning the US Open. The Briton held his serve without any trouble to wrap the set 7-5. Then Murray's terrific defensive lob stretched a point until Wawrinka's forced forehand error. When Wawrinka netted a forehand return, Murray had the 69-minute first set-the first set Wawrinka dropped in the tournament.
Not only has Nadal not conceded a set, he has dropped a total of only 29 games along the way.
Murray was tossing the ball up when umpire Carlos Ramos gave it.
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He fought his way through the first set - Wawrinka was the better player for those first 68 minutes but Murray was the stronger fighter - and he regrouped and rallied after losing seven games in a row at the end of the second set and at the start of third.
Murray seemed to be running out of gas, but he still had plenty of heart left.
"It's incredible to be back to the finals here again". But back he came, taking the third break point of a compelling seventh.
But something will have to give against Wawrinka. "He played good, but he was a bit nervous and tense", said Toni Nadal, who coached his nephew to 14 Grand Slam titles.
Thiem, whose elegant single-handed backhand had little effect throughout the contest, had break points early in the second set but Nadal slammed the door shut.
That set was the first lost by Wawrinka all tournament, but he moved on quickly enough.
Wawrinka restored parity when he prevailed 7-3 in the fourth-set tie-break, forcing a deciding set.
The last French player in the tournament, 28th-seeded Caroline Garcia, is facing No. 2 Karolina Pliskova on Court Philippe Chatrier.
And so to another tiebreak.
The lack of match-wins and indeed match fitness for Murray started to tell - Wawrinka was energised with Murray beginning to look decidedly tired. A lot of long points.
For much of their 4 1/2 hours of compelling, lengthy and draining points, Murray was up to the task, relentlessly defending and making Wawrinka hit shot after shot after shot.