More on our new signing
The 21-year-old keeper has joined Reds on a two-year contract.
Yusuf moved from Millwall Under-18s side to Liverpool for a substantial fee in 2011 and then moved to the Reds' under-21 team where he was a prominent figure in the 2013-14 campaign.
He moved to Turkish Premier League side Kasimpasa in 2014, but did not feature for the Turkish Premier League side.
NUMBER ONE: Mersin made 22 appearances for Liverpool’s U21 side in their 2013-14 campaign.
HIGHLY RATED: Mersin moved from Millwall to Liverpool for a fee reported to be nearly £1million in 2011.
WATCH: Click here for footage of Yusuf in action