The clash spanned nearly four hours on a makeshift Louis Armstrong Stadium as the Australian battled through a back problem and a break deficit in the fifth set to oust the American number two.
Sock let loose on 76 unforced errors through the war of attrition and was forced to save two match points in the fourth set. He forced a decider through a combination of improved discipline from the baseline and apprehension from Thompson but the 23-year-old, mentored by Lleyton Hewitt who cast a watchful eye in the stands, displayed tremendous fighting spirit to reach the second round of a Grand Slam for only the third time in his career. Thomas Fabbiano of Italy awaits.
The Australian produced a mammoth shock when he dispatched Sock at the Davis Cup earlier this year and he was striking the ball with similar conviction to that day during the opening frame.
The all-important break arrived in the sixth game when Thompson constructed his first break opportunity and Sock, more miss than hit off his forehand, sent one long.
He then staved off an immediate break back point from the American before punishing a lax Sock in the very next game to close out the set. The world number 16 produced an inopportune double fault before Thompson produced an immense dig from the deuce corner to conclude the opening set.
Sock, as expected, rallied to open set two and raced out to a 4-1 lead behind a renewed freedom from the baseline. However, a markedly loose game offered Thompson a glimmer of hope before the Australian fashioned two break points in the eighth game to level terms. He duly obliged and a tie-break would be forced to separate the pair.
Mini-breaks were traded before Sock took a 4-2 buffer to the changeover but Thompson raised his level to force a set point on his own deal. He coughed up the opportunity and Sock likewise blew chances to close out the set; four set points went amiss before Thompson found himself with set point at 13-12.
A taxing exchanged followed before Sock netted a forehand on the run and Thompson was staring at a place in the second round. The American, though, had different ideas.
The third set flew past in a flash as Sock – this time – made full use of his double break but the fourth set swung backward and forwards.
The pair traded breaks before Thompson constructed the first of two match points with a lovely executed volley. He squandered that one before a backhand sailed long on a second match point. Sock held for 5-5 and then struck in the twelfth game to force a decider.
A backhand down the line proved the difference – only his second backhand winner all evening – and the fifth set proved a fitting microcosm of the near-four hours of action.
Breaks were traded and it appeared Sock’s superior fitness levels would prevail as Thompson received treatment on his back but the Austrian battled through the pain and recovered the break to set up a grandstand finish.
Sock’s forehand went amiss and a quality return from Thompson on match point silenced the partisan crowd and sunk the 23-year-old to his knees.