Having lost two of their opening seven league games in a campaign for the first time since 2014/15, Real headed into the contest nine points adrift of leaders Barcelona.
Keen to start clawing back that deficit, Los Blancos came flying out of the blocks against Villarreal, and the hosts should’ve taken the lead inside seven minutes, only for talisman Kylian Mbappe to fire wastefully against the post from six yards.
Armed with the confidence of having opened the scoring in each of their last seven LaLiga outings on home soil, Real continued to threaten as the first half progressed.
Mbappe saw another promising chance thwarted by Peter Gulacsi after good work in the build-up by Trent Alexander-Arnold, while Ibrahima Konate and Arda Guler both directed wayward efforts off target.
Having left the field to jeers at the break, Los Blancos looked to up the ante at the start of the second period, with Jose Mourinho introducing Marc Cucurella and Vinicius from the bench.
It was the visitors who threatened before the hour mark, though, as Alberto Moleiro powered a strike narrowly wide and Thibaut Courtois stood firm to deny Pape Gueye.
Those chances proved to be a wake-up call for Real, and the hosts soon took the lead in the 64th minute when Diomande controlled a neat pass from Federico Valverde and drilled a clinical finish into the bottom corner for his first goal since his big-money summer move.
Buoyed by the breakthrough, Los Blancos thought they’d doubled their advantage nine minutes later as Vinicius converted from Jude Bellingham’s cut-back.
However, in truly remarkable circumstances, VAR disallowed the goal after the Brazilian was seen to pull Nathan Saliba’s hair in the build-up, with Vinicius receiving a straight red card as a result.
Despite that setback, Mourinho’s men spurned a glorious chance to put the game to bed when Mbappe was denied at close range by Gulacsi, while at the other end, Georges Mikautadze shot straight at Courtois as Villarreal pushed for a late leveller.
For all the visitors’ pressure, however, the Real rearguard ultimately held firm to clinch a vital three points, extending their unbeaten record in head-to-heads to seven matches (W6, D1).
Flashscore Man of the Match: Federico Valverde (Real Madrid)