Rafael Nadal's Australian Open hopes were dashed in cruel fashion as he retired through injury in the fifth set of his quarter-final against Marin Cilic.
Former US Open champion Cilic produced a hugely impressive display on Rod Laver Arena, his stinging, flat forehands a particularly potent weapon throughout a contest that was brought to a premature end after three hours and 47 minutes.
However, the Croatian was significantly aided by a clear deterioration in the fitness of Nadal, whose movement was compromised after he called for a medical timeout in the fourth set.
Although Nadal initially continued after receiving prolonged treatment on his upper right leg, he was ultimately unable to compete and retired when trailing 3-6 6-3 6-7 (5-7) 6-2 2-0.
Cilic will now face surprise package Kyle Edmund in the last four, with hopes of a rematch of last year's final between Nadal and Roger Federer having been sensationally ended.
The seriousness of Nadal's injury remains to be seen, but the top seed cut a forlorn figure as he exited the court to sympathetic applause, a day on from an ailing Novak Djokovic suffering defeat to Hyeon Chung.
Nadal failed to initially capitalise when a succession of Cilic errors provided him with five chances to break in the sixth game, but the world number one soon seized control before sealing the opening set with a forehand winner.
Cilic then fell behind early in set two, double faulting on break point after receiving a time violation, but a swift turnaround followed with the Croatian seemingly fired up by the umpire's intervention.
The aggrieved sixth seed duly reeled off four games in a row to level the match, enjoying particular success against Nadal's second serve as he adopted a more aggressive approach.
Amid rising tension, both men were showing emotion on an increasingly regular basis and a reflex volley from Nadal was followed by a trademark fist pump as he stopped the rot in the first game of the third set with a crucial hold.
After saving three break points and spurning a solitary opportunity of his own when leading 5-4, there was an even bigger reaction when the Spaniard eventually regained the advantage at the end of an absorbing tie-break.
Nadal let out a huge roar to celebrate putting away a smash on set point, but Cilic came storming back once again to break for a 3-1 lead in the fourth.
Out of the blue, Nadal then called for a medical timeout at the next changeover and received prolonged treatment.
His movement was significantly limited thereafter, even though he came from 0-40 down to hold in the next game, and Cilic suddenly looked a strong favourite as he broke again to force a decider.
That final set ultimately lasted just two games, Nadal bringing an end to proceedings after he had bravely saved five break points before finally falling 2-0 down.
Cilic now has a golden opportunity to reach his third grand slam final, while Nadal will await news on another painful injury setback.
Cilic  bt Nadal  3-6 6-3 6-7 (5-7) 6-2 2-0 Ret.
Cilic - 83/62
Nadal - 39/32
Cilic - 20/8
Nadal - 3/2
BREAK POINTS WON
Cilic - 5/19
Nadal - 2/10
FIRST SERVE PERCENTAGE
Cilic - 67
Nadal - 75
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Cilic - 77/38
Nadal - 67/32
Cilic - 157
Nadal - 145
|Ranieri backs Sarri to succeed at Chelsea|
|Konta admits to doubts after another early Roland Garros exit|
|Warriors´ Iguodala, Looney listed as questionable for game seven|
|Zverev batters Berankis, Goffin back from the brink in Paris|
|Rose cruises to victory at Colonial|
|Neymar: I´m not at 100 per cent yet|
|Toulouse confirm Ligue 1 survival with win over Ajaccio|
|I know what I´ve achieved - Bale not worried about plaudits as he looks to the future|
|Ostapenko ´angry´ after Roland Garros exit, Venus Williams falls at first hurdle|
|Barcelona B relegated to Spain´s third tier|
|Rayo Vallecano win promotion to LaLiga|
|Tarkowski leaves England camp for hernia surgery|
|Ramos ´quite clever´ but Salah injury not to blame for final defeat, insists Robertson|
|WATCH: Ricciardo takes wide receiver role on yacht for Tom Brady pass|
|Until next year – Ronaldo drops new future hint as Real Madrid celebrate with fans|
|Froome stunned by Giro triumph|
|The Triple Crown: Froome´s Grand Tour glory in numbers|
|Hannover sign Wimmer on season-long loan|
|Inter powerless to stop Icardi exit, admits Spalletti|
|Ashton makes England statement with Barbarians hat-trick|
|Watson masterclass seals third IPL title for Super Kings|
|Kozlova ends Ostapenko´s Roland Garros reign on day one|
|Imperious Zverev breezes into second round|
|Froome wins Giro d´Italia to complete Triple Crown|
|Stricken Salah confident over World Cup hopes|
|Verstappen highlights change in approach amid Rosberg criticism|
|Strinic claims three-year deal at Milan|
|Napoli captain Hamsik considering China offer|
|Chinese outsider Wang shocks Venus Williams in Paris|
|Redemption two years in the making - Ricciardo revels in Monaco glory|
|Flawless Molinari holds off McIlroy at Wentworth|
|Karius ´infinitely sorry´ but thanks Liverpool fans for support|
|Root and Bayliss dismiss ´outrageous´ fixing allegations|
|Giggs: Bale the best Welsh player I´ve seen|
|Ricciardo ends Monaco hoodoo despite mechanical issue|
|Lyon star Fekir denies being close to Liverpool switch|
|Pogba: I learned a lot from Abou Diaby|
|Where next for Real Madrid stars Ronaldo and Bale?|
|Shingler and Hewitt out of Wales tour|
|Kyrgios pulls out of French Open|
|Khan wants to bow out by winning blockbuster Brook fight|
|Is winter coming? Game of Thrones stars descend on Monaco|
|Root urges England´s batsmen to ´find a way´|
|Lovren, Van Dijk absolve Karius of blame|
|We all know where our nipples are - Hansen welcomes tackle trial|
|Rooney would thrive in MLS, says DC United boss|
|Pakistan complete demolition of sorry England|
|Curry, Durant reveal the secret to Thompson´s success|
|Salah will miss World Cup, claims Saudi sports administrator|
|Deschamps marvels at Zidane´s incredible Champions League success|
|FIA satisfied Ferrari ´inside the rules´|
|NSW Origin hopeful Moylan pulls the strings for rampant Sharks|
|Champions League blunders will stay with Karius - Clemence|
|Warriors assuming Iguodala won´t play game seven, Kerr says|
|Lampard confirms Derby talks over vacant managerial position|
|French Open 2018: The science behind Nadal´s clay-court dominance explained|
|Walsh to continue as Bangladesh head coach|
|Bale makes emphatic point after Champions League omission|
|Casemiro: I bet Ronaldo stays at Madrid|
|Brewers pull away for blowout win over Mets|
|Warriors´ outburst sinks Rockets, forces game seven|
|MLS Review: Timbers win sixth straight, Techera scores hat-trick|
|It was like wrestling – Klopp unhappy with Ramos challenge on Salah|
|McKinnon says 49ers aiming to win Super Bowl this season|
|Choo makes history with walk-off home run, Rangers seeking ball|
|Shin-Soo Choo makes history with walk-off home run, Rangers seeking ball|
|Marcelo: I think Cristiano Ronaldo will stay at Real Madrid|
|Miller-Uibo shines as Semenya sets record in Eugene|
|Rose extends lead as Spieth slides|
|Prompt recovery, Salah – Ramos wishes Liverpool star well|