The Portuguese coach saw his side edge out their city rivals in an evenly disputed contest at Vallecas to bring up a half-century of victories in just 62 Primera Division matches
Madrid triumphed at Vallecas thanks to Cristiano Ronaldo's wonderful improvised backheel and moved provisionally 13 points clear of title rival Barcelona ahead of the Catalans' clash at Atletico later on Sunday.
Mourinho's 50th win came in only his 62nd Primera Division match, with six draws and six defeats in the other 12 games.
Madrid has now won nine away games this term in La Liga, equaling a record set last season, and could conceivably surpass the 100 points mark in 2011-12, having won an impressive 21 of 24 Primera Division fixtures in the current campaign.
JOSE MOURINHO | 50 WINS IN LA LIGA
Meanwhile, Cristiano Ronaldo's strike was the Portuguese's 123rd goal in 125 official matches for the Santiago Bernabeu side.
The 27-year-old now has 29 goals in 24 league fixtures, meaning he is well on target to beat his own record of 40, which he set last season. In total, the Portuguese has netted 37 times in 36 games for Mourinho's side this term.
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