The 41-year-old Darcis' playing career in the Davis Cup spanned 12 years, and he won 23 of his 35 singles rubbers, including the deciding match against Argentina in the 2015 semi-final.
He was also a key figure as Belgium punched above their weight again to reach the 2017 final, which, as in 2015 against Britain, ended in defeat this time by France, with Darcis suffering the agony of losing the deciding fifth rubber.
He is now Belgium's captain, and his team are one step from another appearance in the final of the men's team competition after a win against France in the quarter-finals in Bologna on Tuesday.
While he cannot physically win any points, Darcis's presence on the court-side bench was a huge factor as Raphael Collignon and Zizou Bergs beat higher-ranked opponents for a 2-0 win.
"I think the bench helped me a lot," said Collignon, who came from a set down to beat Corentin Moutet on the opening day of the Final Eight in Bologna.
"My coach and captain also helped me on the bench. When I'm doubting, when it's tough during the match, he (Darcis) has the right words."
The 23-year-old Collignon, ranked 86th in the world, tapped into the Darcis spirit to claim his third singles win in this year's Davis Cup, having beaten Alex de Minaur and Aleksandar Vukic as Belgium stunned Australia in September to book their place in the Final Eight.
"Since I was a kid, I was watching every tie from Belgium," Collignon said. "I was watching my idols, like David (Goffin). Also Steve, my captain now. I always wanted to play this competition.
"It was at the start a dream, then it became a goal when I was getting higher ranked and better in my country."
Darcis will now prepare the so-called Red Aces for the semi-final against either hosts and holders Italy or Austria and, while their team perhaps lacks superstars, he believes they can make history and win the Cup for the first time.
"Italy is missing its two best players in Jannik Sinner and Lorenzo Musetti but they're still a fantastic team," Darcis said. "They have a lot of options but in the Davis Cup, anything can happen. We'll be ready to give it our all on Friday. We want to go as far as possible."
