The barmaid, played by Jennifer Metcalfe, is currently getting her life back on track as she plans her dream wedding with footballer fiancé Riley Costello (Rob Norbury).
However, in the coming weeks a stunning blonde named Alex will catch Riley's eye during a night out. As she makes a move on him, a drunken Riley revels in the attention - but whether he will go all the way and cheat on Mercedes remains to be seen.
Actress Annie Cooper - who has previously appeared in Coronation Street, Married Single Other and Skins - has been cast in the role of Alex.
Pictured: Annie Cooper as Alex
Speaking of her new part, Cooper commented: "I am delighted to be joining the glamorous cast of Hollyoaks as naughty minx Alex. She's really going to test Riley and Mercedes's relationship and it's exciting to see how it all turns out."
Meanwhile, a Hollyoaks statement teased: "Alex only has one thing on her mind, but which wannabe WAG will reign supreme and at what cost?"
Cooper will be seen on screen as Alex from the beginning of April.
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