David Goffin produced a majestic display to shock hampered world number one Rafael Nadal in an ATP Finals thriller on Monday.
Goffin had not won a set in his previous two matches against the 16-time grand slam champion, but caused an upset with a 7-6 (7-5) 6-7 (4-7) 6-4 win in Group Pete Sampras.
There were doubts over whether Nadal would be fit for the season-ending event due to a knee injury which forced him to withdraw from the Paris Masters and he winced increasingly as seventh seed Goffin turned on the style in London.
Goffin was thrashed by Novak Djokovic after stepping in to replace the injured Gael Monfils for one round-robin match last year, but rose to the occasion against the top seed after becoming the first Belgian to qualify for the singles in the prestigious tournament.
It remains to be seen if Nadal, who battled like a champion to save four match points in the second set, will be able to continue his quest for a first ATP finals title at the O2 Arena.
It was Goffin who claimed the early advantage, breaking in the third game following a couple of Nadal errors, but he undid the good work by drilling a backhand into the net following a double fault to be pegged back at 3-3.
Goffin broke again to go 6-5 up after unleashing a sublime backhand winner only to once again throw in a couple of double faults to ensure a tie-break would settle the first set.
Both players were nervy in a breaker which the Spaniard led 2-0 before going 5-3 down and it was Goffin who struck first to take the set when his opponent netted a backhand.
Goffin's own backhand was proving to be a potent weapon and Nadal was left startled after the world number eight came up with a breathtaking forehand winner en route to claiming a break which gave him the chance to serve out the match.
Yet another Goffin double fault gave two-time runner-up Nadal a vital break back, but the underdog fizzed another sumptuous backhand winner to earn a first match point.
Nadal dug deep to hold and was clenching his fist after saving another three match points from 0-40 in his next service game, going on to raise his game in the tie-break on this occasion after Goffin double-faulted again at a key moment.
The favourite's knee was clearly causing him problems in the final set and he was punished for too many errors, one of which put Goffin a double-break up at 4-1.
Nadal hung in there and broke back, but Goffin marched on and finally put the Mallorca native out of his misery with a 14th ace.
Goffin  bt Nadal  7-6 (7-5) 6-7 (4-7) 6-4
Goffin – 39/43
Nadal – 27/42
Goffin – 14/7
Nadal – 2/2
BREAK POINTS WON
Goffin – 5/13
Nadal – 4/4
FIRST SERVE PERCENTAGE
Goffin – 64
Nadal – 65
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Goffin – 75/54
Nadal – 66/46
Goffin – 113
Nadal – 100
|Sock, Isner and Raonic crash out at Delray Beach|
|Rain sees Cilic-Monfils suspended at crucial stage|
|Djokovic steps up rehab as Federer leads the way|
|Cuban fined $600K for tanking comments|
|Fowler says PGA National demands full attention|
|Rory McIlroy curbing expectations before Masters|
|Shakhtar would´ve won by more if not for Roma´s Alisson – Fonseca|
|Popovich would be ´surprised´ if Leonard returns for Spurs this season|
|Championship Review: Wolves squander two-goal lead to Norwich, Cardiff City take advantage|
|Mourinho happy with ´big effort´ from Pogba|
|Benneteau ousts Bautista Agut in Marseille|
|Mourinho questions medical staff after ´bad´ Herrera injury|
|Sarri demands better from Napoli ´buffoons´|
|Mourinho hugs reporter for asking about McTominay instead of Pogba|
|Di Francesco slams Roma: I should have substituted half of them!|
|Curtains for Konta and Ostapenko in Dubai|
|De Gea happy with ´important´ wonder save|
|Woods eager to experience Masters ´rush´|
|Vazquez and Asensio important to Madrid, says Zidane|
|Shakhtar Donetsk 2 Roma 1: Fred stunner seals first-leg comeback|
|Sevilla 0 Manchester United 0: De Gea ensures Mourinho´s men stay level|
|Klaasen and Duminy half-centuries set up T20 decider|
|Herrera injury gives dropped Pogba chance for reprieve|
|Tindall urges England to ´hunt´ vulnerable Scotland|
|Firmino insists he did not abuse Holgate|
|Leganes 1 Real Madrid 3: Casemiro inspires comeback for Zidane´s men|
|Milan have everything to lose – Gattuso worried about complacency|
|United a big team in defeat - Mourinho aims dig at City|
|Firmino escapes punishment after Holgate allegation|
|Mourinho benches Pogba for Sevilla clash|
|Cavendish withdraws after Abu Dhabi crash|
|Rugby greats put on show in French Alps snow|
|Gremio refute claims of €40m Arthur agreement with Barcelona|
|Messi will sign another Barcelona contract, predicts Bartomeu|
|UEFA rejects PSG appeal over Rabiot´s Real Madrid booking|
|Hardaker sacked by Tigers after failed drugs test|
|James to miss ´a few days´ of Bayern training with calf injury|
|Bellew not feeling Haye love|
|Nantes not stopping Ranieri if Italy come calling|
|Milan owner Li slams ´fake news´ over financial woes|
|Italy make three changes for France encounter|
|Wenger still gunning for top four spot with Arsenal|
|AFC Champions League Review: Kanazaki braces inspires Kashima|
|Gloucester centre Scott to re-join Edinburgh|
|Ospina to get Wembley nod as Wenger waits on Ramsey|
|Pogba not struggling at United, claims Deschamps|
|No police action against Gloucester coach Ackermann or son after nightclub incident|
|Australia proved a point with tri-series dominance, says Warner|
|Escape Messi´s shadow? Change sport! - Henry´s advice to Neymar|
|Scotland unchanged for crucial Calcutta Cup clash|
|Horsing around: Muller takes tips from equine companion|
|Lynn set for further assessment on dislocated shoulder|
|Ronaldo jets off for a break as Madrid head to Leganes|
|Bastareaud back in one of five France changes|
|Mistake to let Kroos leave Bayern for Madrid - Sammer|
|Short´s fifty and Agar´s spin seal deserved Australian tri-series win|
|Spalletti tips Ancelotti for Italy job|
|I can´t wait for retirement - Federer|
|Mendy on course for World Cup, says Deschamps|
|Man Utd on dismal knockout run, Roma have Shakhtar curse - Champions League in Opta numbers|
|Azpilicueta hoping for greater fortune at Camp Nou|
|Out of nothing he can score goals – Heynckes hails Muller|
|CONCACAF Champions League Review: Giovinco inspires Toronto, Tigres held|
|Steelers LB Shazier says he´s ´best linebacker ever´|
|Ranieri: I´ll quit Nantes if offered Italy job|
|Thiem keeps title defence on track, Monfils saves match point in Rio|
|Barcelona are great even without Neymar – Willian|
|Del Potro, Raonic progress at Delray Beach|
|Dolphins place franchise tag on Landry|
|Colts QB Luck ´extremely optimistic´ about shoulder rehab|