Amsterdam, Feb 14 (IANS): Real Madrid, chasing a fourth consecutive Champions League title, needed a goal in the final minutes to pull out a 2-1 win against Ajax Amsterdam in the first leg of their round-of-16 tie.

Real also got help from the Video Assistant Referee (VAR), which made its first significant intervention in Europe's elite club competition with the era sure of an Ajax goal in the first half here on Wednesday, Efe news reported.

Buoyed by the 54,000-plus fans thrilled to see the return of Champions League knockout-stage football to Johan Cruyff Arena after more than a decade, the hosts were electric in the first half.

Real Madrid struggled to play out from the back and the handful of opportunities they got on the counter came to nothing. Ajax goalkeeper Andre Onana, who has been struggling in the domestic league, was never seriously troubled in the first half.

Defensive lapses by the visitors set the tone, often forcing Gareth Bale and Vinicius Junior to drop back and help. And when they didn't, Ajax ran riot.

Only the cross-bar stopped Dusan Tadic from putting the home side ahead and it took a fine stop by keeper Thibaut Courtois to deny Ajax defender Noussair Mazraoui after a giveaway by Sergio Ramos.

Courtois likewise had to be sharp to smother a shot by Hakim Ziyech just seconds before the Belgian international conceded off a corner kick.

The Real Madrid custodian turned aside Matthias de Ligt's header off the Daley Blind corner, but Nicolas Tagliafico was there to hammer in the rebound to make it 1-0 for Ajax in the 37th minute.

Ajax players and supporters went wild, but the celebration ended abruptly when referee Damir Skomina disallowed the goal after an extended look at the replay on the sideline VAR monitor.

He ruled that a slightly offside Tadic had obstructed Courtois.

Real Madrid were vastly better after the break and Karim Benzema tested Onana in the culmination of a play that began with a pass from Dani Carvajal to Luka Modric.

Unable to maintain their frenetic first-half pace, Ajax largely ceded possession to the visitors and the seemingly inevitable goal came at the hour mark.

Vinicius sliced through the defense and charged across the area before leaving the ball for an onrushing Benzema to put the visitors up 1-0.

The three-time defending champions tried to put the match to bed, but Ziyech got equalizer in the 75th minute and Ajax looked poised to secure the draw until Marco Asensio, who came on for Benzema, scored in the 87th minute with an assist from Carvajal.