With the score at 1–1, Rúnar Alex let Riyad Mahrez's free kick slip through his arms to put Manchester City back in front.

[7][8] After first choice goalkeeper Bernd Leno was sent off against Wolverhampton Wanderers on 2 February 2021, Rúnar Alex made his Premier League debut as a substitute for Thomas Partey in a 2–1 away defeat.

[9] On 31 August 2021, Rúnar Alex joined Belgian First Division A club OH Leuven on loan until the end of the season.

[12] On 18 August 2023, Rúnar Alex joined Championship side Cardiff City on a season long loan.

[14] Rúnar Alex made the move to Danish side Copenhagen on 1 February 2024 via a free transfer.