Video footage of Madonna's Lady Gaga reference from her MDNA world tour has emerged online.

Eyebrows were raised when audio appeared online from Madonna's tour rehearsals of the singer performing a mash-up of her track 'Express Youself' and Lady Gaga's 'Born This Way'.

Gaga's track has previously been criticised for drawing a little too much inspiration from 'Express Yourself'.

Madonna opened her MDNA world tour last night (May 31) in Israel and performed the Gaga ditty as expected.

The tour is set to hit the UK in July with shows planned in London, Birmingham and Edinburgh.