Miley Cyrus has ''impressed'' Patrick Schwarzenegger's mother.

The 'We Can't Stop' hitmaker - who is believed to be dating the 21-year-old son of Arnold Schwarzenegger and Maria Shriver - has reportedly started to ''warm up'' to the idea that the two are an item.

A source revealed to ''Maria is still not convinced that Patrick should be focusing all his attention on Miley and isn't thrilled that a romance is brewing.

''But she is warming up to the idea that her feelings may change because she was impressed with the way Miley handled herself during the AFI event.

''There is still a lot more convincing to be done but cracks in the armour have begun.''

Meanwhile, sources have revealed that the pair are rumoured to be in a ''casual'' relationship but are having ''so much fun''.

A source recently said: ''They don't have a title. They are having so much fun together that friends don't know at certain times if they are a couple or best friends.

''They can go for a length of time without seeing each other, and then they are spending every waking moment together.''

Another source added: ''They might seem like an odd pairing, but they are quite good for each other. They've been friends forever.''