creep up
US /kriːp ʌp/
UK /kriːp ʌp/

1.
esgueirar-se, subir gradualmente
to move slowly and quietly so as not to be noticed
:
•
The cat crept up on the bird.
O gato se esgueirou até o pássaro.
•
Prices have been creeping up steadily.
Os preços têm subido constantemente.