Kyrgios took out the first set 6-4 only to be outlasted in a decisive tie-break and final set in the second round of an ATP event in Stuttgart, Germany, one of many leading into the 2026 Wimbledon Championships which begin in late June.
Following a first round straight sets win over rank no. 36 Corentin Moutet earlier in the week, Kyrgios declared himself "great and motivated" following multiple knee surgeries and a wrist reconstruction that kept him out off the circuit for the best part of three years.
"It's quite an emotional moment," he said at the time.
"But I’m back mostly because of the fans. I’m staying for you guys.”
The controversial figure reminded tennis fans of his best and his worst on court against Shimabukuro, showing off his flair and showmanship including a lookaway volley in the first set that drew laughter from the crowd and from Kyrgios himself.
Things turned sour later in the match when an under-pressure Kyrgios lashed out at the chair umpire in the third game of the deciding set, claiming he should have been alerted that it was the final game before a change of balls were to be introduced.
He challenged the umpire's ruling that it was not a common convention or requirement for chair umpires to make such an announcement.
“I’m pretty sure it used to be a thing," said Kyrgios, who was playing just his third competitive tournament outside of Australia since the 2023 running of the Stuttgart Open.
“I don’t know if you’re new or anything, but (for) as long as I’ve been on tour, the game before, it’s been like ‘new balls next game’“
“That’s courtesy. You know how you hold us accountable, I think we should hold you accountable too, yeah?”
Kyrgios was unable to hold his nerve, losing his final service game of the third set to do down 6-4 6-7(5) 4-6.
He has had no shortage of brushes with match officials and tennis authorities over the years, once holding an unwanted record for the biggest fine in ATP history when forced to cough up US$113,000 (AU$160,000) for a raft of offences at the 2019 Cincinnati Masters.