Alexander Zverev produced a majestic performance to claim the biggest title of his career and deny Novak Djokovic a record-equalling ATP Finals success on Sunday.
Djokovic had not been broken in London or dropped a set this week, but the magnificent Zverev struck a big blow for the next generation by winning a high-quality final 6-4 6-3.
World number one Djokovic was unable to match Roger Federer's tally of six triumphs at the season-ending event as his 21-year-old opponent rose to the occasion with a nerveless display.
The German was booed after stopping mid-point in a second-set tie-break when a ballboy dropped a ball during his semi-final win over Federer on Saturday, but he turned jeers into cheers by denying Djokovic a glorious end to a resurgent season.
Zverev, comfortably beaten by Djokovic in the round robin stage on Wednesday, won 79 per cent of points on his first serve as he claimed a fourth title of a season in which he has won more matches than any other player.
The third seed showed no signs of nerves on the big stage as both players started with vigour, serving superbly and trading punches from the baseline.
There was not a sniff of a break point in a service masterclass until Djokovic let his usual high standards slip at 4-4, drilling a forehand long and crashing another into the net to give Zverev the chance to serve out the set.
The world number five grasped his opportunity emphatically, firing down three aces and clenching his fist after another wayward groundstroke saw Djokovic lose a first set of the week.
Zverev maintained his momentum with the 14-time grand slam champion looking vulnerable and broke in the first game of the second set with a searing forehand winner to end an epic rally.
The Serbian broke straight back, but gifted his youthful opponent the initiative immediately with a poor attempted drop shot followed by a tired looking forehand into the net.
Zverev consolidated the break on this occasion to lead 3-1 and Djokovic was unable to find a way back.
A fittingly sublime backhand winner from Zverev ended a pulsating contest, the two rivals embracing after the new champion had dropped to the court with a weight seemingly lifted off his shoulders.
Zverev  bt Djokovic  6-4 6-3
Zverev - 23/18
Djokovic - 7/20
Zverev - 10/3
Djokovic - 1/1
BREAK POINTS WON
Djokovic - 1/1
FIRST SERVE PERCENTAGE
Djokovic - 60
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Zverev - 79/54
Djokovic - 74/35
Zverev - 57
Djokovic - 46
|Hero Rivers feared he had cost Chargers in KC|
|Williams would welcome Llorente back to Athletic Bilbao|
|Liverpool v Manchester United: Minding the gap|
|Milan elimination unjust, fumes Leonardo|
|Paul hails ´sick´ Harden after record-breaking display|
|Liverpool v Manchester United: Salah, Mane and Firmino v Rashford, Martial and Lukaku in Opta number|
|Canelo open to GGG trilogy as he chases place in Mexican history|
|The big Friday Premier League quiz|
|Harden posts record fourth 50-point triple-double in win over Lakers|
|Barcelona squad happy with Dembele, says Alba|
|Chargers rally past Chiefs to clinch playoff spot|
|WATCH: Chargers top Chiefs on dramatic two-point conversion in final seconds|
|Suns owner Sarver committed to keeping team in Phoenix|
|Chargers WR Allen leaves with injury after near-spectacular catch|
|Socceroos not giving up on Mooy for Asian Cup|
|Cooper says Raiders owner wanted to trade him to Cowboys|
|Pochettino jokes Levy is ´worried´ about losing him|
|Barcelona would welcome Morata – Alba|
|Toure not a priority for West Ham – Pellegrini|
|Koscielny no certainty to face Southampton, says Emery|
|We gifted the game – AC Milan boss Gattuso furious after Europa League exit|
|My season starts now, says Koscielny|
|Cipriani ´at peace´ with latest England snub|
|Laporte: Deschamps must have personal reasons for France snub|
|Morata injury not too serious, claims Chelsea boss Sarri|
|Hansen to leave: All Blacks coach returning focus to World Cup defence|
|I want to fight the champion! - Joshua reiterates Wilder in April ambition|
|Gundogan glad to leave Christmas holidays behind|
|I know how it feels and it hurts - Gundogan on Sterling abuse|
|Celtic 1 Red Bull Salzburg 2: Scottish champions through despite defeat|
|Olympiacos 3 AC Milan 1: Rossoneri crash out of Europa League|
|Arsenal 1 Qarabag 0: Lacazette on target as Saka shines|
|Hansen to leave: All Blacks will take time to name replacement|
|Chelsea condemn alleged anti-Semitic chanting from fans|
|Hansen to leave: The best Opta facts from New Zealand coach´s tenure|
|Hansen to leave: Five contenders to be the next All Blacks coach|
|Hansen to leave: Highs and highs of his All Blacks reign|
|Hansen to leave All Blacks after World Cup|
|Rapid Vienna 1 Rangers 0: Late Ljubicic winner sends Gerrard´s men out|
|Beckham continues to miss Giants practice with quad injury|
|Vidi 2 Chelsea 2: Giroud spares Sarri´s side in lacklustre draw|
|Paris Saint-Germain and Marseille fixtures among latest Ligue 1 cancellations|
|Santos turn to ex-Argentina boss Sampaoli|
|Muller could miss Champions League last 16 after Tagliafico kick|
|Home hope Bekker out in front at Alfred Dunhill Championship|
|Van Bommel in touch with Robben over PSV reunion|
|Pinarello chief confident over Team Sky future|
|Stade make Ospreys tickets free in tribute to teenager|
|WRC great Loeb seals Hyundai switch|
|Madrid rumours better than sack talk, says Pochettino|
|Nadal to join Federer at 2019 Laver Cup|
|Prigoda smashes world record, Hosszu dethroned in Hangzhou|
|Former Juve CEO Marotta takes over at Inter|
|Glenn to stand down as FA boss next year|
|Muller apologises to Tagliafico for kick to the head|
|Pereira pleads for more Manchester United chances|
|Griffin hails ´phenomenal´ Lowry after Warriors demolition|
|I´ve played with Zidane and Henry, but Messi is something else – Pires|
|Dragons forward Jack de Belin charged with sexual assault|
|Durant: Raptors are the real deal|
|Cocu bids farewell to Fenerbahce after ´mutual agreement´ is made over October sacking|
|Australia unchanged for historic Perth Test|
|Champions League draw: The possible last-16 ties|
|Southee happy to be back on home soil|
|I wouldn´t swap Dembele for Neymar – Pires|
|Canelo ready to risk heavy weather against Fielding|
|Raptors upstage Warriors, Davis leads Pelicans with 44 points|
|India skipper Kohli excited by green Perth wicket|
|PSG? I haven´t decided my future yet – De Jong|
|Marcelo: Real Madrid don´t have attitude problem|