| K-1 Grand Prix '98 final round | |
| Promotion: | K-1 |
| Date: | December 13, 1998 |
| Venue: | Tokyo Dome |
| City: |  Tokyo, Japan |
| Attendance: | 63,800 |
| Previousevent: | K-1 Japan '98 Kamikaze |
| Followingevent: | K-1 Rising Sun '99 |
K-1 Grand Prix '98 final round was a martial arts event promoted by the K-1. The event was held at the Tokyo Dome in Tokyo, Japan, on Sunday, December 13, 1998, in front of 63,800 spectators. It was the sixth K-1 World Grand Prix final involving eight of the world's best heavyweight fighters (+95 kg/209 lbs), with all bouts fought under K-1 rules. The eight finalists had all qualified via elimination fights at the K-1 World Grand Prix '98 opening round. Also on the card was a number of 'Freshman Fights' fought under a mixture of Jiu-Jitsu Freestyle and K-1 rules (various weight classes). In total there were eighteen fighters at the event, representing seven countries.
The tournament winner was Peter Aerts who won his third K-1 Grand Prix final by defeated Andy Hug by way of first round knockout. Andy would be making his third consecutive final appearance, having won it in 1996 and been runner up the following year.
| Freshman fights 1 + 2: jiu-jitsu freestyle rules / 8Min. 1R | |
| Kazuhiro Inoue def. Toru Hirai | |
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|---|---|
| Yasuki Hiramatsu def. Takayuki Okada | |
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| Freshman fight 3 (-72.5 kg): K-1 rules / 3Min. 3R | |
| Takashi Ohno def. Akira Okada | |
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| Freshman fight 4 (Open Weight): K-1 rules / 3Min. 3R | |
| Masahi Suzuki def. Ryo Kataoka | |
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| Freshman fight 5 (-58 kg): K-1 rules / 3Min. 5R | |
| Hideki Takada def. Susumu Daiguji | |
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| K-1 Grand Prix quarter-finals: K-1 rules / 3Min. 3R Ext.1R | |
Mike Bernardo def. Francisco Filho  | |
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 Peter Aerts def. Masaaki Satake | |
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 Sam Greco def. Ernesto Hoost | |
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 Andy Hug def. Ray Sefo  | |
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| K-1 Grand Prix Semi Finals: K-1 rules / 3Min. 3R Ext.1R | |
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| Andy Hug def. Sam Greco | |
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| K-1 Grand Prix Final: K-1 rules / 3Min. 3R Ext.2R | |
| Peter Aerts def. Andy Hug | |
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