The Portuguese capital is hosting the European Cup (now Champions League) final for the first time since 1967 when Jock Stein and his players became the first British team to lift the trophy. To mark the occasion, Celtic are flying the surviving Lions out to Lisbon and Hughes will be among those on board.
He is enthused about the prospect of meeting up with those he played alongside during a decade of stellar service in a Celtic shirt but it is tempered by a sense of disappointment and regret. Hughes has a winner's medal from that famous victory over Internazionale but doesn't feel like he earned it. An ankle injury kept him out of the final but he is still not convinced Stein would have picked him even if he had been fit.
"I'm looking forward to Lisbon although not playing in 1967 was one of the most disappointing times of my career," he said at the launch of his autobiography, Yogi Bare. "It was terrible not to be involved. You're detached from it and it was terrible afterwards, during all the celebrations.
"You force a smile but, deep inside, it's soul-destroying. Obviously, I didn't want to see the boys lose but I didn't feel part of it when they won. I had a poisoned ankle but I don't think I'd have been playing anyway because I had a bad game in the semi-final against Dukla Prague. They weren't even going to take me with them. When they did, I shared with John Cushley and, when I removed the bandage on my ankle, the poison spurted five feet into the air. So I spent most of my time in my room. But for the club to be taking me back to Lisbon is wonderful."
Hughes is a candid story-teller. After all these years he has regrets and he is not reluctant to reveal them, both in print and in person. The decision by Stein to sell him to Crystal Palace in 1971 still stings him to this day. He did not want to leave Celtic but the manager had other ideas. It is a transfer that has left a bitter taste in the mouth that has never gone away.
"What he [Stein] has done for Celtic no-one can ever change that, it's in the history books," he added. "It was a phenomenal achievement. But he wasn't my favourite person eventually. I didn't go to his funeral. I would have been a hypocrite if I had gone. He got rid of me when I was in my prime and three months later I was finished.
"People say to me, 'are you bitter?' Yes. In the book we've tried not to comment. We've told people what happened and left them to make their own minds up. Then it's not me who's saying it; it's their own opinion. Yes I was bitter. I was finished at 28. I think I'm the seventh highest goalscorer [in Celtic's history] but had I stayed until I was 32 and kept scoring at the same rate I would have been third top.
"I'm a Celtic guy and I didn't want to leave Celtic. Ken Gallacher [the journalist, later of The Herald] had told me that Everton and Sheffield Wednesday were interested in me as well. He asked why I signed for Crystal Palace when other clubs were in for me. I didn't know, he [Stein] didn't tell me. I was negotiating with the Crystal Palace chairman and the boss and he [Stein] came in and took me outside. He said: 'You get in there and f*****g sign or I'll sit you in the stand for nine months.' So that was that. It would never happen nowadays as you've got agents and some sort of say. With Jock you didn't have a say. You know what they say about power corrupting and absolute power. I don't think I'll ever get over what happened."
Hughes plays down talk that he and Stein had a "troubled relationship" but some of the anecdotes in the book do not paint the former Celtic and Scotland manager in the most flattering of lights. "We were on a post-season tour to America in 1966 and my first wife, Mary, was pregnant at the time. I used to phone home every five or six days. Then I bumped into Ken Gallacher one morning and he said, 'sorry to hear your news'. I didn't know what he was talking about and he was the one who told me that Mary had had a miscarriage four days earlier. Jock knew but he hadn't told me. Make your own mind up."
Hughes, on the mend after a recent cancer scare, has retained some good memories, too. He scored in the European Cup semi-final win over Leeds United in 1970, played in the final against Feyenoord (even though Celtic lost) and scored goals by the bucketload season after season. "It was just fantastic playing in that team with so many good players," he recalled. "We were entertaining. People talk about the current side having to play against packed defences but we had to deal with that every week as well, home and away, but we overcame it because we had the ability. We also had three of the highest goalscorers in Celtic's history; myself, Bobby Lennox and Stevie Chalmers - and what you need to remember is that I made most of their goals!"
He had been approached in the past to do a book but never showed any desire. Now 71, he felt the time was right. "I wasn't interested but then one of my sons said it would be a good idea to leave a legacy for my grandchildren. It was very enjoyable. And the book came quite easily."
Yogi Bare - The Life and Times of a Celtic Legend, by John Hughes with Alex Gordon, £18.99