Newcastle have poked fun at the early season discipline of striker Aleksandar Mitrovic in wishing him a happy birthday.

The Serbian was booked in his first two games for the club, and was sent off in the fifth match, before receiving another yellow while playing for his country.

Newcastle tweeted a happy birthday to him and then said "he's received lots of cards".

Happy 21st birthday to Aleksandar Mitrović! 🎂🎉 He's had lots of cards... #NUFC pic.twitter.com/I3BkllX3Aa

— Newcastle United FC (@NUFC) September 16, 2015