The ball slowly went over the net and into the opposite service box, but a perplexed Kyrgios was left rooted to the spot in bewilderment, as did those present in the crowd, while the umpire called "Game, set, and match" in a 6-3 6-4 victory for Tomic.
Tomic won the exhibition 6-3 6-4, with the hit-and-giggle nature of the contest summed up best by a truly outrageous final point.
Serving for the match, Tomic bounced the ball in preparation for a regular serve before flicking an underarm shot between his legs.
Tomic delivered one of the craziest finishes ever seen in a tennis match.
But the pair faced off in a low-key matchup that served as a useful warm-up for their respective campaigns at the upcoming Australian Open in Melbourne.
Tomic's first set was nearly flawless, while Kyrgios looked a little underdone and struggled to find some rhythm early on.
With his silky hands and superb touch, Tomic broke for a 3-1 lead and then steamed through the first set.
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The US team was led by Deputy US Trade Representative Jeffrey Gerrish, who is reportedly closely aligned to Lighthizer. The US delegation included representatives from the departments of energy, agriculture, treasury and commerce.
Kyrgios, who lost in the second round at the Brisbane International last week, had a break point early in the second but was unable to consolidate with Tomic then breaking at 3-3.
Now ranked 85, Tomic finished the year in style with an ATP title in China.
"I'll get on site at Melbourne Park, fine-tune my game a little bit and make sure the body's right".
"I think it's an exciting time for Australian tennis as we've got such a wide variety of players". However, Tomic finished the 2018 season on good terms as he won the Chengdu Open file and returned to the top-100.
"It is great to see him back out here as I know he was going through some rough times", world number 51 Kyrgios, who himself has struggled for consistency, added.