Brazilian Malcom, who started in place of Lionel Messi, curled home in the 58th minute to pull Barcelona level after Lucas Vazquez had fired Real Madrid ahead early on.
Vazquez struck after just six minutes to silence the Nou Camp at the end of a slick team move, with Santiago Solari’s side impressing in the opening stages.
However, Ivan Rakitic clipped the crossbar with a header as Barcelona fought for an equaliser and Malcom eventually found it when Luis Suarez’s shot rebounded to him off the post.
Messi, who suffered a thigh injury at the weekend against Valencia, appeared for the final half hour but could not help champions Barcelona find a late winner.
"Speaking generally, the draw was fair," said Barcelona midfielder Sergio Busquets.
"It was very even, everything will be decided in the second leg. There were chances for both sides to win the game. It's 50-50, even though they're at home.
"The goal will give (Malcom) a lot in terms of confidence, we hope that everyone in the squad can help us."
Malcom has struggled for game time since joining from Bordeaux last July as he is behind Messi, Suarez, Ousmane Dembele and Philippe Coutinho in the pecking order.
However, Messi's injury gave him the chance to impress and the 21-year-old was Barcelona's liveliest player, always probing at Madrid's defence.
Wednesday's result would also have gone some way towards healing Real's wounded pride as their last visit to the Nou Camp ended in a 5-1 La Liga thrashing last October in what turned out to be Julen Lopetegui's final game in charge.
"Both sides have the chance to go through," said Madrid goalkeeper Keylor Navas, who made good saves from Suarez and Malcom.
"It was a good game. Everyone on the team worked hard when we needed to and we played well too."
The second leg takes place on Feb. 27 at the Santiago Bernabeu.
(Editing by Pritha Sarkar)
