The German won his second major European trophy in a matter of months with Chelsea as the Blues defeated Villarreal 6-5 on penalties after a 1-1 draw in 120 minutes of action.
As extra time came to a close and penalties loomed, Tuchel took a leaf out of Louis van Gaal's book when he took off first-choice goalkeeper Mendy and sent on Kepa for spot-kicks in the 119th minute.
It proved to be a quite sublime call as the Spaniard saved two penalties, denying Aissa Mandi and Raul Albiol, to win the trophy in Belfast.
Incredibly, Tuchel admitted the substitution was completely planned and something he had been thinking about since his first knockout game back in February.
"It was not spontaneous," Tuchel told BT Sport post-match.
"We talked about it with the goalkeepers when we came in the first cup game against Barnsley. We had some statistics.
"We were well prepared that Kepa has the best percentage at saving penalties.
"The analysing guys, the goalkeeper coaches showed me and introduced me to the data and then we spoke to the players and told them it could happen in cup games.
"We spoke to the players and Edou was fantastic. We do what we need to do for the team.There is proof that Kepa is better in this discipline and these guys are true team players.
"I am happy for Kepa and for Edou to have a goalkeeper like this that does not show the pride to not step off the field. He is happy to do this for the team and take this for the team."
For Kepa, the contrast to the 2019 Carabao Cup was quite remarkable. On that day at Wembley, he was set to be make way for Willy Caballero ahead of the shoot-out against Manchester City but refused in an infamous incident that had Maurizio Sarri losing his head.
This time, however, he was the hero and finally got his moment in Chelsea colours after coming in for criticism ever since his £72 million move from Athletic Bilbao.
And Mendy's attitude was nothing short of brilliant. He supported his teammate before the spot-kicks and raced over to celebrate when he made the match-winning save.
"I'm happy because we won and we worked for this success," Mendy said while he and Kepa took part in a joint interview with BT Sport.
"I knew since last year that if Kepa came on the pitch he would help the team. He did today and I'm really happy."
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