With his side seemingly down and out, trailing 2-0 on the night and 3-0 on aggregate, Lucas produced a career-defining performance as his stunning second-half hat-trick engineered the latest jaw-dropping Champions League comeback to send Spurs through on away goals.
Yet scarcely 18 months ago, he was at a particularly low ebb after finding himself frozen out in Paris despite five trophy-laden years at the club.
Mauricio Pochettino and Tottenham offered the Brazilian an escape route in January 2018, and Lucas is close to making good on his promise to take the club to the very top.
Upon his arrival in North London, he said: "I think the team is very, very strong. We can win a lot of things and why not the Champions League?"
Just over a year on and Spurs are one win away from becoming European champions after Lucas conjured up a display at the Johan Cruyff Arena befitting of the late Dutch great.
"They are all heroes but Lucas was a super-hero. Unbelievable hat-trick. He deserves it, he is a great guy," a tearful Pochettino said after Tottenham's 3-2 win in Amsterdam set up a June 1 final with fellow comeback kings Liverpool.
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Tottenham midfielder Christian Eriksen even called for a statue of Lucas, who dragged Spurs back from the brink with what were remarkably his first Champions League knockout goals.
Ajax, 1-0 winners in London, appeared home and dry after surging a further two goals clear in the return leg, but Lucas had other ideas with a quickfire double on the hour.
That gave Spurs hope but they were still heading out until Lucas squeezed a low shot beyond Ajax goalkeeper Andre Onana in the 96th minute to earn his place in Tottenham folklore.
"Football gives us moments like this that we cannot imagine," said Lucas. "We need to enjoy it. Look at me -- it's the best moment in my life, my career.
"It's impossible to explain what I am feeling. I am very, very happy and proud of my teammates.
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"We always believed in this moment, that it was possible. We gave everything and deserved this moment. We are a family. It's impossible to explain -- impossible."
He became just the fifth player to score a hat-trick in a Champions League semi-final, after Alessandro Del Piero, Ivica Olic, Robert Lewandowski and Cristiano Ronaldo.
Billed at his PSG unveiling as a talent on par with Neymar, Lucas left France without truly fulfilling his potential, but he has now shown their loss is very much Tottenham's gain.
"It's not a response. Criticism is part of football. I knew I could play for a big club, that I was capable of playing in the semi-finals of the Champions League," he said.
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