"It happened to me last week on match point and it happened again yesterday," said Mannarino. "When you are thinking about not making double faults, for sure you are going to make it. I wish sometimes I had no brain."
He will need to avoid any mental wobbles today against Jiri Vesely, after the Czech qualifier continued his giant-killing run, taking down world No 16 Kevin Anderson in the second semifinal. The 21-year-old Vesely was good value for the 6-4 7-6 (4) victory, in another intimidating display of power tennis.
It is the first meeting between the two, who will both also be playing in their first finals at ATP tour level.
The 26-year-old Mannarino has had success at Challenger level but admits a victory today would be a whole new level.
"I'm pretty old now," said Mannarino. "[Making a final] is an achievement for sure but winning a tournament would be the best one. Winning a tour event is completely different."
Pouille was the crowd favourite yesterday but didn't reach the heights of his previous matches earlier this week. After being parachuted into the tournament as a lucky loser he had been hugely impressive, taking care of New Zealander Michael Venus and world No 61 Albert Ramos-Vinolas in straight sets.
But the encounter with his compatriot was always going to be difficult. The two know each other well - they are regular practice partners - and their respective coaches are good friends.
"Every time I have played someone coached by his coach I have lost," said Mannarino.
"And [Lucas] told me before the match - I know exactly how to beat you."
Though there were some fantastic rallies, the match never reached any great heights, perhaps because both players were equally desperate. Mannarino, after 10 years as a professional, is yet to win a title and the semifinal yesterday was his first in almost four years. Meanwhile Pouille knew that a place in the final would propel him into the top 100.
Pouille was out of sorts in the first set. He was going for his shots but they were landing wide or long, instead of winners. The veteran Mannarino was happy to soak up the pressure, get the ball back in court and wait for errors. The strategy worked for the first set - Mannarino secured a break and held on. He should have sealed the match in the second set but blew an early break chance.
"The match was really intense," said Mannarino. "I was trying to stay focused but I was going a little crazy. I felt like I had the match in my hands but I didn't take my chance."
After Pouille took the second set the momentum seemed to be with the youngster. He looked the more likely winner and Mannarino was on edge.
"I was most of the time on the defence and he had nothing to lose," said Mannarino. "He was pushing, pushing and I didn't feel like I was controlling the match. [In the end] it wasn't a question of experience, it was a question of bravery."
