past master
US /pæst ˈmæs.tər/
UK /pæst ˈmæs.tər/
1.
maestro, experto
a person who is very skilled or experienced in a particular activity or subject
:
•
He's a past master at negotiation, always getting the best deal.
Es un maestro en la negociación, siempre consigue el mejor trato.
•
She's a past master at making excuses.
Es una maestra en poner excusas.