Gareth Bale scored on his debut for Real Madrid but Carlo Ancelotti's side could only draw 2-2 with Villarreal away from home in La Liga.
The Wales international winger, who joined the Spanish giants from Tottenham Hotspur in the summer for a world-record £85m transfer fee, found the target in the 39th minute.
Villarreal had started the contest the brighter of the two teams and surged ahead on 21 minutes through Cani, who collected a loose ball inside the Madrid box and slammed it home.
However, the visitors soon began to increase their pressure and equalised through Bale before the break, the 24-year-old turning home a Daniel Carvajal cross.
Jaume Costa almost restored the Yellow Submarine's advantage 10 minutes into the second half with a shot that went just wide, and Cristiano Ronaldo punished them for that miss.
The Portugal international forward was quick to collect a parried save from Sergio Asenjo and found the target with the help of a deflection.
However, Giovani dos Santos made it 2-2 in the 70th minute after Diego Lopez had turned a save from a Cani effort onto his path.
Madrid poured forward in search of their third and potentially winning goal, but failed to make their chances count.