Kanye West serenaded his new fiancée Kim Kardashian during his concert on Tuesday night (22.10.13).

The rapper treated Kim, the mother of his four-month-old daughter North, to a musical tribute just 24 hours after popping the question to her on her 33rd birthday on Monday (21.10.13).

Kim and her mother Kris Jenner attended Kanye's 'Yeezus' concert in San Francisco, California, and Kanye took the opportunity to declare his love to his wife-to-be as he performed his song 'Bound 2', which he wrote about their romance.

Introducing the track, he told the crowd: ''You know what song this is, right? I want to sing this song to the birthday girl that's back there right now, my fiancée.''

The suggestive track's lyrics refer to Kim as a ''good girl'' who ''is worth a thousand bitches''.

Loved-up Kanye, 36, appeared to be in a jubilant mood after getting engaged as he also dispensed love advice to his fans.

He mused on the microphone: ''If you came with somebody that you love tonight, hold on so tight. What I'm trying to say is it's hard to find.''

The 'Jesus Walks' rapper proposed to Kim at the AT&T Park stadium in San Francisco on Monday (21.10.13), presenting her with a lavish 15-carat diamond ring.

Kim gushed about her engagement: ''[It] was truly magical. I am the luckiest girl in the world, I get to marry my best friend.''