Dominic Thiem gained revenge after back-to-back final defeats with a stunning 6-4 6-3 win over seven-time Internazionali BNL d'Italia champion Rafael Nadal.
The Austrian was beaten by Nadal in his maiden ATP Masters 1000 final at the Madrid Open, having already been defeated by the same opponent at the same stage of the Barcelona Open.
But the honours belonged to the supreme Thiem in Friday's quarter-final meeting in Rome, the 23-year-old producing a heavy-hitting display that frequently had Nadal chasing shadows in his first clay-court loss of 2017.
Novak Djokovic or Juan Martin del Potro will be up next for Thiem in the last four.
Thiem – whose solitary win in this head to head came at last year's Argentina Open – was quickly into his stride, a couple of vicious one-handed backhands helping him to an opening-game break, even as Nadal landed all six first serves.
The pinpoint accuracy of Thiem's early play soon had him 2-0 up and putting pressure on the Nadal serve once more, taking the 14-time grand slam champion to deuce.
Remarkably, the world number seven simply continued to get better and Nadal initially had no answer to his opponent's power and precision from the baseline, which earned another break for a 4-1 lead.
It was then that Nadal finally had some joy against the serve, but Thiem kept his cool at 40-40, with the Spaniard forced to all corners of the court before being outdone by a thunderbolt forehand winner.
Having shown signs of life in clawing one game back, Nadal – returning to stay in the set – started with two ferocious winners and saw Thiem send one long to give the King of Clay two break points.
Although they were snuffed out, Nadal dug deep and profited from some rare Thiem errors to cut the gap, which was further reduced following a prompt hold.
Serving for the set for the second time, Thiem produced a more accomplished game to halt Nadal's fightback and move ahead.
Nadal wasted little time in testing Thiem's nerve in the second set, a deft drop shot and a powerful forehand down the line taking it to deuce in the right-hander's opening service game, though he did ultimately hold.
An increasingly animated Nadal knew he had to vary his approach and began to show a greater willingness to come to the net as he sought to disrupt the inspired Thiem's rhythm, a tactic that yielded mixed results.
One such venture forward resulted in Nadal dumping the ball into the net and he proceeded to lose the next two points to trail 15-40 on serve, before battling back for a gutsy hold.
But when he stepped up to serve at 3-3, Nadal suffered a decisive loss, one exchange leaving the crowd on their feet as Thiem raced behind the baseline and rifled a cross-court backhand past his rival.
Thiem stayed strong in the face of break points to see out a thrilling contest with a last break of his own, as Nadal wrapped up his French Open preparations with a shock loss.
IMPRESSIVE ZVEREV SETS UP ISNER SEMI
Alexander Zverev continued his promising season, which has yielded two ATP Tour titles, with a fine 7-6 (7-4) 6-1 win over Milos Raonic.
The German, who turned 20 last month, recovered from the blow of failing to serve out the opening set to win a tense tie-break against the 2016 Wimbledon finalist.
Raonic faded badly in the second set of the first meeting between the pair, the seven games taking just 28 minutes to complete.
Zverev will now face John Isner following the American's battling triumph over Marin Cilic.
Isner prevailed 7-6 (7-3) 2-6 7-6 (7-2), with the help of 21 aces, to record only his second win against the Croatian.
|Gattuso: Milan have to put helmets on and go into battle against Arsenal|
|Klopp tells in-form Liverpool to ´stay angry´|
|Harvick dominates rain-delayed race in Atlanta|
|Thomas outlasts List in play-off to win Honda Classic|
|Neymar injury? I played the ball, claims Sarr|
|Higginbotham banned for three weeks, Reds team-mate Tui faces hearing|
|Change in approach was key to impressive Milan win - Gattuso|
|If Griezmann grows, we all grow - Simeone hails Atletico´s Sevilla rout|
|Neymar to face Real Madrid despite ankle injury, expects Emery|
|Cavani worried about Neymar ankle injury|
|Tiger Woods ´very pleased´ with Honda Classic showing|
|Silva: Neymar a doubt for Coupe de France quarter-final|
|Hat-trick hero Griezmann dreaming big in Atleti´s title bid|
|Before a manager I´m a human being - Guardiola explains continued ribbon protest|
|Neymar carried off on stretcher in PSG injury blow|
|Red-hot Schwartzman races to Rio Open glory|
|Paris Saint-Germain 3 Marseille 0: Neymar injured in easy Classique win|
|Roma 0 AC Milan 2: Cutrone and Calabria secure superb win for Rossoneri|
|Sevilla 2 Atletico Madrid 5: Griezmann hat-trick sinks sorry hosts|
|Tiafoe takes out first title in Delray Beach|
|Wenger trolled by Wembley official in Man City humbling|
|Wenger goes easy on Mustafi, despite Wembley woe|
|It´d be a dream - Henry wants Arsenal manager´s job|
|Man City just getting started, warns De Bruyne|
|Mind the goose! Tiger Woods collects birdies in more ways than one|
|Wenger rues early Aubameyang miss after Wembley humbling|
|Gary Neville blasts ´spineless´ Arsenal after EFL Cup final|
|Neymar shakes off virus to start for PSG in Le Classique vs Marseille|
|Guardiola sets sights on further silverware after ´outstanding´ EFL Cup triumph|
|EFL Cup social round-up: Men against boys and Wenger Out|
|Kompany: Winning EFL Cup makes injury nightmare worthwhile|
|I´ve signed for a football team, claims Usain Bolt|
|Van Gaal dismisses Chelsea rumours as ´fake news´|
|Toulon claim notable scalp with victory at La Rochelle|
|Reliability first - Renault to limit initial engine potential|
|Arsenal 0 Manchester City 3: Guardiola thrashes Wenger for first English trophy|
|Pochettino plans throw-in practice for Aurier|
|Conte hints at unhappiness with Hazard work-rate in Man Utd loss|
|Terrific Tigers tame Sarries to close in on top four|
|Mourinho v Conte: All smiles and handshakes on the touchline as feud cools|
|Mourinho hails Lukaku display against old club Chelsea|
|Depleted Rhinos slump to defeat at Widnes|
|Mourinho on Conte handshake: It doesn´t need words|
|Conte demands VAR after Morata sees Old Trafford equaliser ruled out|
|Pochettino defends ´easy target´ Alli after Van Aanholt clash|
|Juventus v Atalanta postponed due to snow|
|Criticism never affected me - Lukaku revels in comeback Man Utd win|
|Khachanov claims Marseille title to deny Pouille a home double|
|Guardiola wears yellow ribbon at Wembley despite FA charge|
|Cardiff extend winning run at Zebre|
|Manchester United 2 Chelsea 1: Lukaku and Lingard complete Old Trafford comeback|
|Chambers in as Wenger picks back three at Wembley|
|Pochettino satisfied with ´deserved´ Tottenham victory|
|Six Nations to investigate Scotland-England tunnel incident|
|It´s getting boring! - Dier lauds Kane following last-gasp winner|
|Lukaku finally makes big-game breakthrough for Manchester United|
|€70m not enough to prise Milinkovic-Savic from Lazio|
|Tah pens Leverkusen extension until 2023|
|Cardiff City 1 Bristol City 0: Zohore the hero again as Bluebirds win derby|
|Crystal Palace 0 Tottenham 1: Late Kane header snatches victory|
|Morgan praises Stokes´ comeback performance|
|Skriniar sees himself at Inter ´for many years´|
|Pogba, Martial start for Manchester United as Chelsea bring back Morata|
|Aluko under consideration as Neville offers Sampson critics ´clean slate´|
|Inter did not invent Icardi injury, Spalletti insists|
|Gilberto Silva: Wilshere´s mental strength key to success|
|Lewandowski: Agent change nothing to do with ´funny´ Real Madrid talk|
|Barcelona´s Semedo facing five weeks out with hamstring injury|
|Winter Olympics 2018: Bjoergen takes record-equalling gold as Norway top medal table|
|Dier has no regrets over Manchester United snub|