IKER CASILLAS has vowed that Jose Mourinho might be an uncomfortable ride on his return to Porto.
Mourinho steered the Portuguese outfit to Champions League glory in 2004.
Casillas has had first experience of working under Mourinho during his time at Real Madrid.
Chelsea have been drawn alongside Dynamo Kiev and Maccabi Tel Aviv in Group G.
But Casillas has sent Mourinho and his men a warning.
“Chelsea is a hard rival and normally will be the favourite in the Group but I have learned that in the Champions League nobody is comfortable,” Casillas said as quoted by the Daily Mirror.
Mourinho failed to lift the Champions League during his time at the Bernabeu.

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