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In a Madrid derby defined by three moments of outstanding individual brilliance, Diaz's contribution proved to be decisive ahead of the second leg next week. 

Rodrygo put the hosts ahead inside four minutes at the Bernabeu when he sprinted past Javi Galan, chopping inside before bending a wonderful effort past Jan Oblak.

But after a nervy start to the contest, Atletico quickly settled and restored parity in the 32nd minute with a stunning goal of its own via Julian Alvarez.

The in-form striker skipped beyond Eduardo Camavinga's challenge on the right before whipping a spectacular curling strike around Thibaut Courtois and in off the post.

Diego Simeone's side missed a glorious chance to edge ahead in the second half after a mistake by Antonio Rudiger, but Rodrigo De Paul was unable to capitalise.

That spurned opportunity was punished two minutes later when Diaz, in for the suspended Jude Bellingham, skilfully waltzed into the box before driving a low shot into the far corner.

Real Madrid should have increased its lead heading into the second leg late on when Kylian Mbappe raced through on goal down the right, but his cutback to Vinicius Junior was intercepted by Marcos Llorente.