The likeable Australian, ranked No.175 in the world, claimed the biggest win of his career as he ended Roger Federer’s Miami Open title defence 3-6 6-3 7-6(4) at the second round stage.
It was a gutsy display from Kokkinakis, who once doubted whether his shattered body was capable of coping with the rigorous demands of top-flight action. His perseverance has finally paid off though, and his unexpected success should instil confidence and belief.
Federer was attempting to banish memories of his painful defeat in the final of the BNP Paribas Open last weekend, but instead, he suffered the indignation of an unwanted record.
Kokkinakis has become the lowest ranked performer in 15 years to overcome a reigning world No.1.
Federer’s forehand, just as it did in the Juan Martin del Potro loss, was prone to mistakes and his youthful opponent simply outgunned him. The Swiss has enjoyed a glorious start to the season, however he is not performing to the same level he did 12 months.
His second successive defeat means Rafael Nadal will become world No.1 again when the ranking are updated. It might only be a short stay at the top of the pile for the Spaniard, though, as he has a sizeable chunk of points to defend in the upcoming clay-court season.
The Swiss made a promising start to the contest and sealed the opening gambit by six games to three. Kokkinakis, who made just 42% of first serves in the first set, warmed to his task as the duel progressed.
The Australian negotiated a tricky first service game in the second set before making his move. Federer assisted his rival’s cause by misfiring from the baseline, and the underdog moved 3-1 ahead.
Kokkinakis had an opportunity to extend his lead and establish a double-break, but his opponent resisted his advances. It was nothing more than a minor blow for the 21-year-old – and he was soon level on the scoreboard.
The third set was tight and a tiebreak was eventually necessary. There were more errors than winners in the shootout, but that didn't bother the delighted victor.
Kokkinakis exploded with joy after converting his first match-point, and few will begrudge the Australian his moment in the spotlight.
Earlier in the day, Kyle Edmund suffered a narrow loss to Frances Tiafoe. The British No.1 served for the match in the third set, but faltered and paid a heavy price.
The American thrilled the crowd as he sealed a 7-6(4) 4-6 7-6(5) victory.
Alexander Zverev, still searching for his best form after a difficult start to the campaign, squeezed past Daniil Medvedev 6-4 1-6 7-6(5). Tomas Berdych, David Ferrer, Fernando Verdasco and Karen Khachanov are also safely through to round three.
In the evening session, Nick Kyrgios, in his first match outing since early February, thrashed Dusan Lajovic 6-4 6-1 in just 49 minutes.
Kevin Anderson, Borna Coric, Fabio Fognini, Sam Querrey, Denis Shapovalov, Jack Sock, Pablo Carreno Busta and Steve Johnson also registered victories.