The 1986 FIFA World Cup Mexico™ was hugely important for the North American country, which made history by becoming the first nation to host the tournament twice, having previously done so in 1970.

On the pitch, El Tri made a deep run, reaching the quarter-finals unbeaten, where they faced Germany, who would ultimately go on to reach the final before losing to Argentina. Mexican hopes were dashed in the tightly contested tie that ended in a goalless draw after extra time, exiting the tournament after losing 4-1 on penalties.

For the nation it was a bitter end, but for one man, Humberto Sierra, the experience was sweetened and he treasures the memory. A referee at the time, the Mexican had signed up as a volunteer at the FIFA World Cup™ to support the refereeing team.

“We were given a vehicle to drive the referees. We were notified when they would be arriving at the airport and had to be there to meet them. We took them to the hotel and asked whether they wanted to see the city.”

This is how he met Jesús Díaz Palacios, the Colombian referee who would officiate that infamous quarter-final match on 21 June 1986 at Monterrey’s Estadio Universitario. After the game, he did something that Humberto will never forget.

Humberto reminisced: “My main memory from that World Cup is that quarter-final match. The stadium was packed to the rafters. We were talking to the referees on our way to the stadium. They were discussing their game plan, and I remember there being a lot of traffic.

“When we arrived at the stadium, the referees went into the changing room, and we stayed outside. It was such a wonderful feeling. Even though I wasn’t wearing a referee kit – I was in a suit – I felt like part of the team.”

He reaches the part of the story that marked the end of Mexico’s dreams: a time of grief for the host nation and an occasion that will be etched in Sierra’s memory forever. His face lights up as he recalls one particular moment, though: “The match ended, and then this incredible thing happened. The referee said goodbye to everyone. He turned to the linesman and said: ‘Here, this ball is for you.’ He gave another one to the other assistant referee and one to the commissioner, Roger Marchand from France. Then he told me, ‘Humberto, this ball is for you.’” Sierra is visibly moved as he holds the ball and retells the story.

“I thought, ‘What an unbelievable memento of my time at this World Cup.’ I’m very proud of it. For me, it’s as priceless as a trophy.”

Over the years, the ball has become a relic that fascinates everyone who sees it.

“I’ve had this ‘trophy’ for a long time and I’ve told the story to my children more than once. People often ask me about it. They ask whether this was the ball with which [Francisco Javier] Cruz scored the disallowed goal or whether it was used during the penalty shoot-out. I don’t know. But I do know it was used at some point during the match. That World Cup was the first time they allowed five balls to be used.”

He explained: “One ball would go out, so another would come into play. At some point during those 90 minutes, the 30 minutes of extra time or the penalty shoot-out, this ball was used. I’ve treasured it. At first, it was a beautiful memory. Now, it is a source of pride, it’s very dear to me.”

At the time, Sierra was already a professional referee. “I officiated in the first division and I earned the FIFA badge,” he said, proudly presenting it. He belongs to the first generation of assistant referees. The 1986 World Cup marked the beginning of a rewarding career that gave him the opportunity to officiate on the international stage.

He is also proud that the FIFA World Cup has returned to Mexico and Monterrey, with both the nation and the city embracing the tournament for a third time.

“We are passionate about football, but we’re also welcoming and friendly. That’s one reason why they decided to come back for this edition. In 1986, we warmly welcomed fans from all over the world, and I think that was a very convincing reason for FIFA to award the (FIFA) World Cup to Mexico as co-host.”

Sierra was able to relive the World Cup atmosphere at the Group A match between South Africa and South Korea at Monterrey Stadium, where he was particularly impressed by the pre-match ceremony.

“There’s something new at every edition. In this tournament, seeing both national flags spread across the pitch, all the players, the starting XI and substitutes, walking out together, standing there for the anthems, greeting the referees... we’ve never seen these things at a World Cup before. These types of innovations by FIFA will raise the standard even further for future tournaments.”

A referee to his core, when asked about the match, he answered: “I was there as a fan, but my mind was still focused on the refereeing. I watched how the referee ran, the decisions he made – I can’t help it. A booking, a free-kick, a throw-in... I find myself narrating the game through the referee’s actions.”

His refereeing career began almost by accident.

“I was working at the Universidad Autónoma de Nuevo León, and my immediate supervisor was an instructor for professional referees. He gave me a copy of the Laws of the Game, and I was fascinated. I started training with professional referees. I enjoyed the discipline and the structure.”

His career went from strength to strength. “What attracted me most was the discipline and ensuring fairness. I’ve had a rich career: one season I was named the best linesman in Mexican football. Later, in the second division, I won the award for best referee and was promoted to the first division. In 1992, I became part of the first generation of assistant referees, and in Monterrey I was the first referee in history with a FIFA badge,” he explained, showing the badge and photos of the international matches at which he officiated.

He sees how refereeing had changed significantly over the years, mentioning one innovation in particular that has improved the FIFA World Cup experience: “In my day, the rule book was very thin – 17 laws and a few instructions. It’s gotten quite a bit thicker. Many things have changed, including the introduction of VAR, which is an excellent technological innovation. If changes to the Laws of the Game help referees or improve the game, then they are more than welcome.”