Although he was usually smaller than his opponents, standing at 1.80 m (5 ft 11 in) and being barely a heavyweight, weighing around 98.0 kg (216.1 lb; 15.43 st) in his prime, he made up for his lack of size with his tremendous athleticism and speed.

[4][5] Raised in Wohlen, Aargau, Hug was a keen footballer in his youth but gave up the sport to pursue Kyokushin karate which he began practicing at ten years old.

Beginning his full contact karate career in the 80 kg/176 lb middleweight division, he rose to prominence in the late 1970s and early 1980s by winning numerous regional tournaments around Europe and made the transition to heavyweight in 1984.

That same year, he competed in the Kyokushin World Open, knockdown karate's most prestigious competition, for the first time and made it to the fourth round where he was eliminated by Shokei Matsui.

After winning the 1992 Seidokaikan Karate World Cup, beating Taiei Kin in the final, and finishing as runner-up to Masaaki Satake in the 1993 edition, Hug then transitioned to K-1 kickboxing, scoring a first round knockout of Ryuji Murakami in his professional debut at K-1 Andy's Glove in November 1993.

[10] Following his breakout performance in the Oyama Cup, Hug earned himself a place on the Swiss national Kyokushin team and then became the co-founder of a dojo in Bremgarten aged seventeen.

After reaching the round of sixteen in both the 2nd European Championships and the 6th Dutch Open, being eliminated by Jean-Pierre Louisset and Kenneth Felter respectively, Hug closed out the year by being crowned champion at the 1st Ibusz Oyama Cup in Budapest, Hungary where he defeated Mark Niedziokka in the final.

Andy Hug returned to the World Open in November 1987 and made history by becoming the first gaijin to reach the final of the tournament, booking his place with a judges' decision win over Akira Masuda in the semis.

Undefeated as a Seidokaikan fighter, Hug entered the K-1 Illusion 1993 Karate World Cup on October 2, 1993, defeating Yoshinori Arata, Changpuek Kiatsongrit and Toshiyuki Atokawa on his way to the final where he met Masaaki Satake.

Following the tournament, Hug began his transition from full contact karate to kickboxing and, already a part of K-1's roster, made his debut against Ryuji Murakami at K-1 Andy's Glove on November 15, 1993.

Struggling early due to his lack of boxing prowess, Hug received a standing eight count from referee Genshu Igari in round one after being rocked by an uppercut from Cikatić.

Hug had a quick turnaround, as he was back in the ring on May 4, 1995, scoring a forty-five second knockout over Peter Kramer in a K-1 World Grand Prix 1995 non-tournament affair.

Hug would then lose in his next two outings, firstly to Ernesto Hoost by majority decision at the K-3 Grand Prix '95 on July 16, 1995, and then Mike Bernardo by KO in a rematch at K-1 Revenge II on September 3, 1995.

After making short work of Duane van der Merwe with a KO inside forty seconds at the tournament's quarter-final stage, awaiting Hug was Ernesto Hoost in the semis and the pair had an epic battle considered to be one of the greatest matches in K-1's history.

At September 1's K-1 Revenge '96, Hug fought the first of his own six Muay Thai matches, challenging Stan Longinidis for his WMTC World Super Heavyweight (+95 kg/209 lb) Championship.

They exchanged heavy strikes in a close first round but Hug then went out and severely outgunned Longinidis in the second, knocking his Australian opponent down with a high kick before viciously finishing the job with a left cross after he beat the count.

Andy Hug's eight fight win streak was brought to an end by then-two-time K-1 Grand Prix champion Peter Aerts in the first of their four meetings at K-1 Kings '97 on March 16, 1997.

He then fought to a five-round split draw with Sam Greco at K-1 Braves '97 on April 29, 1997, before having his fourth and final battle with Mike Bernardo in his first WKA world super heavyweight title defence on June 7, 1997, at K-1 Fight Night '97 in Zurich.

The fight started tense and cagey, with little to no action for the majority of round one until Filho, making his debut under kickboxing rules, landed the decisive strike, a perfectly timed counter right hook, which sent Hug crashing to the canvas in a state of unconsciousness at the 2:37 mark.

The round of eight went down on November 9 and saw the rubber match between Andy Hug and Masaaki Satake in the quarter-finals go just fifteen seconds as the Swiss dispatched his Japanese foe with a high kick.

With his WKA World Super Heavyweight Muay Thai Championship on the line, Hug outfought Aerts over the five rounds to take a unanimous decision and make the second defence of his belt.

In a tune-up fight ahead of the Grand Prix finals, Hug KO'd Masaaki Miyamoto with a spinning backfist moments after dropping him with the same technique at K-1 Japan '98 Kamikaze on October 28, 1998.

Around this time, Hug also turned his hand to training other competitors at his facility in Lucerne, Switzerland, bringing through the next generation of Swiss heavyweights in Xhavit Bajrami, Björn Bregy and Petar Majstorović as well as foreign talent such as Michael McDonald.

[25] Hug then registered back-to-back unanimous decision victories over Stefan Leko, in his third defence of the WKA strap at K-1 Fight Night '99 on June 5, and Maurice Smith, at K-1 Spirits '99 on August 22.

In what would prove to be his final match, Andy Hug scored a quick knockout over Nobu Hayashi at K-1 Spirits 2000 on July 7, 2000, sending his Japanese opponent to the canvas twice inside the first round.

Ilona and Seya moved to the United States where she attended the Santa Monica College of Design, Art and Architecture for two years before returning to Switzerland upon completion of her studies.

Despite the advice of the doctors and his manager Rene Ernst, Hug travelled to Japan on 14 August to train ahead of his planned participation in the K-1 World Grand Prix 2000 in Fukuoka.

The doctors' warnings proved true when, after starting chemotherapy, Hug suffered hemorrhaging of the brain and inflammation of the lungs (pneumonia) combined with extreme fever.

Peter Aerts, who was at the Nippon Medical School hospital having treatment on his lower back at the time, broke down crying for over two hours when told of Hug's passing.

Eight hundred guests including Kazuyoshi Ishii, Hajime Kazumi, Akira Masuda, Shokei Matsui, Kenji Midori and Swiss President Adolf Ogi attended while more than twelve thousand mourners gathered outside.