Betis found themselves down a man before half-time when Paulao was shown his second yellow card following a clumsy challenge on Jose Antonio Reyes.
Real's problems were exacerbated when the resulting free-kick was headed home by Cameroon international Mbia who was fortunate enough to have his header go straight through the hands of Betis goalkeeper Guillermo Sara.
It marked Mbia's first goal for the Andalusia club since joining them on loan from QPR in the summer transfer window. The R's were happy to offload Mbia's large wages following his disappointing stint with the West London club since joining them from Marseille for a reported £5million in 2012.
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