Barcelona 1-2 Real Madrid: Alaba and Vazquez settle El Clasico
Real Madrid returned to the summit of LaLiga as David Alaba's stunner and Lucas Vazquez's late tap in saw Carlo Ancelotti's team beat Barcelona 2-1 in the season's first Clasico.
Sergino Dest squandered a golden chance for Barca at Camp Nou and Madrid made their hosts pay when Clasico debutant Alaba arrowed in a brilliant shot.
Karim Benzema should have added to Madrid's lead in the second half, though Vazquez was on hand to nudge in at the end of a stoppage-time counter.
That proved to be crucial, with Sergio Aguero's maiden Barca goal in the 97th minute not enough to inspire a comeback as the hosts failed to win a fifth straight LaLiga Clasico, their longest winless run against any team in the competition since May 2008.
Barca seemed all set to take the lead after breaking clear from a Marc-Andre ter Stegen pass, yet with only Thibaut Courtois to beat, Sergino Dest lashed a close-range effort way over the bar.
Where one defender failed, another one made no such mistake. After getting Madrid on the counter by dispossessing Memphis Depay, Alaba continued his run to latch onto Rodrygo's pass and thump a wonderful finish into the top-right corner.
Alaba made a telling contribution at the other end before half-time, blocking Ansu Fati's goal-bound attempt after Gerard Pique had headed just wide.
Benzema snatched at a volley just after the hour, before he failed to turn home Vinicius' cross from close range, albeit the offside flag spared his blushes.
Pique and substitute Aguero both flapped at a cutback in injury time and Madrid grabbed a second goal from the resulting counter when Vazquez tucked in on the rebound from Marco Asensio's shot.
Aguero, another Clasico debutant, gave Barca a glimmer of hope, though the final whistle blew a minute later.
What does it mean? More misery for Koeman
Koeman is only the second manager in LaLiga history to lose his first three Clasico matches, after former Barca boss Patrick O'Connell between 1935 and 1940, with the Blaugrana sitting in eighth and already five points off the leaders.
Ancelotti, meanwhile, claimed his first managerial victory against Barca at Camp Nou at the sixth attempt.
David's dream Clasico debut
With his stunning strike, Alaba became the fifth player to score on his Clasico debut for Madrid in the 21st century, after Brazilian striker Ronaldo (2003), Ruud van Nistelrooy (2006), Raphael Varane and Jese Rodriguez (both 2013).
Dest fails to deliver
Starting in an advanced role on the right, Dest should have put Barca ahead in the 25th minute, yet from the best opportunity of the game at that stage (an expected goals value of 0.336, while Alaba's strike had an xG of just 0.081), the full-back fluffed his lines. It was no shock to see him reverted back to the defence in the second half.
Key Opta Facts
Barcelona's Gavi (17 years and 80 days) became the youngest to play a Clasico game in LaLiga in the 21st Century, surpassing Pedri (17 years and 334 days).
Luka Modric became the oldest to play in a LaLiga Clasico in the 21st Century, surpassing the previous record set by Fabio Cannavaro (35 years and 231 days in May 2009).
Alaba scored his first goal for Madrid from his first shot on target in all competitions.
Under Koeman, since the start the last season, Barca have lost five games against Madrid (three) and Atleti (two), as many as in the previous nine seasons in the competition.
Aguero has been involved in five goals in his last six LaLiga appearances against Madrid (three goals and two assists), and he has scored in each of his last three games at home against them in the competition.
A trip to Rayo Vallecano follows for Barca on Wednesday, while Madrid host Osasuna.