A decent first-half display from Champions League debutant Astana was undone by Benfica's Nicolas Gaitan and Konstantinos Mitroglou.
A confident second-half performance saw Benfica begin its European campaign with a 2-0 win over Champions League newcomer Astana on Tuesday.
Nicolas Gaitan opened the scoring in the 51st minute following a neat move involving Konstantinos Mitroglou, with Astana substitute Aleksey Shchetkin having hit the post moments earlier.
A solid first-half display from the visiting side was then further undone when Mitroglou found himself on the end of Eliseu's low cross to tap home.
It was by no means a vintage performance from Benfica, who will need to up its game when it takes on bitter rival FC Porto on the weekend.