[2] On 29 June 2017, Chrien moved to Portugal and signed a five-year contract with defending champions Benfica Lisbon.

[3] The same year on 20 August, he made his 2017–18 Primeira Liga debut against Belenenses in a 5–0 victory, coming on in the 71st minute of the match.

[4] Due to lack of enough playing time, Chrien was linked with a loan move to Croatian clubs Hajduk Split[5] and Osijek.

[8] Chrien received his first call-up to the Slovak senior squad by Pavel Hapal for UEFA Euro 2020 qualifying fixture against Hungary and Wales.

[9] On 7 June 2019, Chrien debuted in a friendly match against Jordan as a starter, scoring the second goal which ended in a 5–1 victory for the Slovaks.