An own goal from Carlos Izquierdoz ensured the first leg of the Copa Libertadores final between Boca Juniors and River Plate ended in a 2-2 draw.
The home side twice surrendered the lead against their fierce rivals in an enthralling encounter at the boisterous La Bombonera in Buenos Aires.
The much-anticipated clash, the first between Argentina's biggest clubs in the final of South America's top club competition, was delayed until Sunday due to heavy rain in the capital.
Boca went ahead through Ramon Abila only to see Lucas Pratto level practically from kick-off, and their advantage was again snatched from their grasp when Izquierdoz's wayward header cancelled out Dario Benedetto's goal.
It leaves the tie tantalisingly poised ahead of the second leg in 13 days' time.
Postales de una tarde INOLVIDABLE en La Bombonera pic.twitter.com/BpQrSu5XfE— CONMEBOL Libertadores (@Libertadores) November 11, 2018
It was River who threatened first, Agustin Rossi keeping out Gonzalo Martinez's free-kick before Lucas Martinez Quarta made a mess of a free header from the resulting corner.
Rossi them denied Santos Borre with a fine one-handed stop, and Boca's difficult start got worse when Cristian Pavon was forced off after 27 minutes with what looked like a hamstring injury.
The Bombonera was rocking 34 minutes in, though. Abila saw a shot saved by Franco Armani, but fired the rebound through the grasp of the keeper and in.
The lead lasted barely 60 seconds, with Pratto racing on to Martinez's pass and firing across goal and into the bottom-right corner.
Another chance for Martinez came and went before Boca snatched the lead again seconds before half-time, Benedetto glancing Sebastian Villa's deep free-kick high into the net.
A similar set-piece routine almost created a third for the home side, only for River to equalise again in similar fashion, when Izquierdoz headed in past the helpless Rossi from six yards out.
Boca introduced Carlos Tevez from the bench and the veteran striker almost provided the winner, first lashing a shot just wide of the left-hand post before teeing up Benedetto to shoot straight at Armani with the goal at his mercy.
What does it mean? River hold slender advantage
Away goals do not count in this final, but River will be happy to head into the home leg knowing a win by any scoreline will be enough to see them clinch the trophy.
The manner in which they responded to falling behind twice will have emboldened coach Marcelo Gallardo, even if he was banned from being present at the match.
Boca will be frustrated not to have held on to the lead on either occasion, and the injury to Pavon will give them more cause for concern ahead of the second leg.
Rossi bails out Boca when it matters most
Rossi only made four saves in total, but all could prove hugely important after 180 minutes of this tie have been played. He could do little about the goals, either.
Martinez Quarta a mess
Having missed a clear chance with a header early on, Martinez Quarta was caught out of position as Abila broke the deadlock. He was taken off after 58 minutes.
All eyes are on November 24, when River will host the second leg at the end of the international break.
|Eibar 2 Barcelona 2: Two-goal Messi moves four clear of Mbappe in Golden Shoe race|
|Dominant Koepka chasing history in final round of US PGA|
|Betis confirm Setien departure|
|Celtic´s Boyata agrees to join Hertha Berlin|
|´I have lived the dream´: Kompany´s best moments at Manchester City|
|Zidane vows to make changes as Navas & Bale face uncertain futures|
|MotoGP Raceweek: Marquez masters Le Mans to make it three wins in four|
|We are the guilty ones - Marcelo says Madrid players must accept responsibility|
|Ten trophies, 360 appearances, 20 goals - Kompany´s Manchester City career in numbers|
|Pliskova seals Rome title with straight-sets win|
|De Bruyne, Neville and a rock ´n´ roll star pay tribute to captain fantastic Kompany|
|Perth Glory 0 Sydney FC 0 (aet, 1-4 on penalties): Redmayne the hero in A-League Grand Final|
|Real Madrid 0 Real Betis 2: Zidane´s men humbled in final-day defeat|
|Joshua-Wilder must be next, no excuses - Hearn|
|Trail Blazers need effort over strategy in Game 4 against Warriors - Stotts|
|Fans to receive 82 per cent of Euro 2020 tickets|
|Green: Arguing with officials made me disgusting to watch|
|Kompany appointed as Anderlecht player-manager|
|World class Kompany is Manchester City´s DNA, says Goater|
|Ponga scores stunning double as Knights thrash Dragons|
|Kompany thanks Guardiola and Manchester City team-mates after announcing departure|
|Kompany leaving Manchester City after 11 years|
|Breazeale feels referee stopped Wilder fight too early|
|Green playing ´unbelievably well´, says Kerr|
|Astros get 10th straight win with defeat of Red Sox|
|Warriors´ Iguodala to undergo MRI as Finals beckon|
|Three takeaways from Golden State´s comeback win over Portland|
|Wilder asks for patience over Joshua fight|
|Warriors on verge of NBA Finals after trumping Trail Blazers|
|Wilder retains title with first-round knockout of Breazeale|
|MLS Review: Rooney scores in DC defeat, Wondolowski breaks record|
|Larson wins $1m NASCAR All-Star Race after qualifying in Open|
|Nurse wants Raptors to ´play their a** off´ and change series|
|My last great moment at Allianz Arena – Ribery revels in Bundesliga triumph|
|Eagles defensive end Long announces retirement|
|Ribery, Robben shaped Bayern & Bundesliga – Kovac|
|Favre left disappointed after Dortmund miss out on title|
|Sancho targets Bundesliga glory with Dortmund next season|
|Koepka has no doubts he´ll win US PGA Championship|
|Johnson looking for ´some help´ from Koepka|
|History awaits as Koepka takes record seven-shot lead at US PGA|
|Of course I will be here – Cavani wants to stay at PSG|
|Saunders targets ´big names´ after becoming two-weight world champion|
|Kane stars as USA close on quarter-final berth|
|Lyon president Aulas urges PSG to make Ndombele move|
|Sylvinho, Juninho to join Lyon as coach and sporting director|
|Dupichot and Zebo grab hat-tricks as Racing 92 rout Perpignan|
|Sensational Inoue hammers Rodriguez to win IBF bantamweight belt|
|Do not steal goals, Raheem! Sterling offers explanation for Pep-talk|
|Ouch! Djokovic embarrassed after accidentally hitting ball boy|
|Ronaldo pays tribute to departing Allegri|
|We need to score that chance - Gracia rues Pereyra miss in City humbling|
|Benfica crush Santa Clara to clinch title and pass 100-goals mark|
|Derby strikes and play-off failings – Wondolowski´s MLS goals record in Opta numbers|
|Goal-shy Piatek must focus on Milan - Gattuso|
|There is a score there for me - McIlroy pleased with improved display|
|Guardiola: Man City treble feat harder than Champions League but can be repeated|
|Djokovic edges out Schwartzman to set up Nadal final|
|Koepka still well clear despite slight Bethpage wobble|
|Paris Saint-Germain 4 Dijon 0: Mbappe closes on Messi with brace|
|Guardiola fumes at payment question after FA Cup win|
|Stormers hold Crusaders to dramatic draw after Lions win thriller|
|Mentally I was done – De Bruyne on injury nightmare|
|Sterling denied FA Cup final hat-trick as Jesus awarded Man City´s second goal|
|Guardiola demands improvement from treble-winning Manchester City|
|Madness – Sterling astonished by De Bruyne´s FA Cup cameo|
|Take another look at Manchester City´s sensational six FA Cup final goals|
|Man City treble: Are Guardiola´s men the best team of the Premier League era?|
|Chiefs finish top as Saints edge out Quins for fourth|
|Runaway leader Koepka starts round three at Bethpage|