Marco Asensio scored a late winner for Real Madrid in a 2-1 victory at Ajax Amsterdam, who were left to rue a goal disallowed by the video assistant referee (VAR) in their Champions League round-of-16 first leg on Wednesday.
Asensio netted in the 87th minute from Dani Carvajal's excellent cross to give Real the advantage heading into the return leg on March 5.
Karim Benzema swept holders Real into the lead in the second half, before Hakim Ziyech scored a deserved equaliser as an energetic Ajax created more than enough chances to win comfortably on the night.
They were also denied a first-half opener when Nicolas Tagliafico headed home but for the first time in Champions League history, the goal was ruled out after Slovenian referee Damir Skomina checked with the VAR and Dusan Tadic was judged offside.
Ajax are seeking to reach the Champions League quarterfinals for the first time in 16 years, while Real have not lost a tie at this stage in almost a decade.
Ajax made the brighter start and should have gone ahead when right back Noussair Mazraoui put his shot wide after finding himself the furthest player forward with only Madrid goalkeeper Thibaut Courtois to beat.
Tadic then held off Sergio Ramos to fire in a shot that hit the post, and Ziyech missed another one-on-one chance with Courtois as Ajax's incisive passing stretched the visitors.
The home side thought they had profited from a horror error by Courtois, who allowed a Donny van de Beek header to spill from his grasp and Tagliafico nodded the rebound into an empty net.
Yet Skomina called for a VAR check and, after a number of replays, ruled that Tadic had been standing in an offside position when the goal was scored.
Benzema tested the reflexes of home goalkeeper Andre Onana just after the break, a warning of his threat that was not heeded as he netted on the hour-mark with a rasping finish into the top-corner after Vinicius Jr. picked him out after having been given acres of space in the box.
Ajax got the goal their play deserved with 15 minutes remaining as Ziyech side-footed home after a sweeping move, latching on to a delivery from David Neres on the left.
Yet Asensio had the final word, scoring at the back post from Carvajal's cross.
Ajax claimed a foul in the build-up to the goal, but this time the VAR did not intervene and Real will take a slender advantage back to Madrid.