Brahim Diaz's second-half winner gave Real Madrid a narrow 2-1 victory over city rivals Atlético Madrid in a fractious first leg of their Champions League Round of 16 clash on Tuesday. The hosts took an early lead through Rodrygo before Julián Álvarez equalized with a sensational strike, but Diaz secured the crucial advantage with a clinical finish inside the box.

The derby encounter lacked fluency as both sides appeared cautious, perhaps reserving energy for next week's return leg at Atlético's Metropolitano Stadium. Real Madrid capitalized early when Rodrygo fired home after just four minutes, but Atlético gradually found their rhythm. Álvarez drew the visitors level in the 32nd minute with a thunderous effort from outside the area.

The decisive moment came in the 55th minute when Diaz exploited a tight opening in the crowded penalty area, slotting a low, angled shot past Jan Oblak. Despite dominating large portions of the match, Diego Simeone's side failed to convert their opportunities, leaving them trailing ahead of the second leg. The result sets up an intriguing return fixture as Atlético aim to reverse the deficit.

The hosts started better and Rodrygo gave them the lead after an outstanding pass by Federico Valverde that he took in his stride before rampaging inside the box past two defenders and curling a brilliant left-foot strike into the far corner.

Despite Real's early dominance, the visitors managed to level the playing field by slowing the pace of the game and started to create chances through Samuel Lino and Giuliano Simeone, a constant menace running up and down the channels.

Atlético found the equaliser after Álvarez wrestled past Eduardo Camavinga on the left byline before cutting inside the box to give himself a better angle and unleashing a strike that curled past Thibaut Courtois and went in off the far post.

The visitors took control of possession and were comfortable passing the ball around amid loud booing from the sold-out Bernabeu crowd who did not hide their frustration.

Atleti began the second half well with Rodrigo de Paul wasting a chance to give them the lead in the 53rd minute, a costly miss as two minutes later Brahim worked his magic to put Real back in front with a goal out of nothing.

Surrounded by three opponents, the Morocco international worked some space with quick feet and left Atletico centre-back José María Giménez on the ground before slotting the ball inside the far corner, giving Oblak no chance.

Simeone appeared comfortable with the scoreline, replacing attacker Antoine Griezmann with centre-back Robin Le Normand and switching to five at the back to make sure Real's lead was no greater ahead of next week's mouth-watering second leg.

"If it was difficult today, imagine how difficult it will be on Wednesday," Real Madrid coach Carlo Ancelotti said after the win. "But we have a small advantage, and we'll try to go through. It will be difficult, not much will change."