The 34-year-old Frenchman has now reached his first ATP final for the season.
Ranked 38 in the world, Simon lost the first set but went on to win 6-7 (4-7) 6-4 6-3 in a game which ran for longer than two and a half hours.
The match will have been a particularly gruelling one for Simon after he needed three hours and 20 minutes to beat Nicolas Mahut i nteh quarter-finals, the longest match in the tournament's history.
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"It was hard to recover for this one," admitted Simon.
"It was tough until the end with long rallies. It was a tough match. But you relax a bit when you're really tired and you've played a long match."
Simon is due to play the winner of Felix Auger-Aliassime and Spaniard Feliciano Lopez in Sunday's final.
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