The Brazil international heads into the Wembley showdown as the Reds’ top player on current form, though he’s not the one making all of the headlines on Merseyside.
That title goes to winger Raheem Sterling, who recently told the BBC of his decision to reject a lucrative new contract which has subsequently led to intense media speculation over his future.
The England international is undoubtedly a top player at Anfield, and the so-called media scrutiny surrounding his every move has arguably relieved the pressure on a number of his teammates.
One man who has profited from going under the radar is former Inter Milan star Coutinho, though his stunning performance against Newcastle United last Monday was difficult to ignore.
Sunday’s opponents Aston Villa will provide a tough test for the Reds and owing to their form, Merson feels they can progress to the final if they manage to contain not Sterling, but Coutinho as well.
“Aston Villa can cause an FA Cup upset against Liverpool tomorrow,” Merson predicted.
“I think they will sit back and counter-attack with the pace of Gabby Agbonlahor and Christian Benteke. Emre Can is a good player but he won’t be able to live with them, and Martin Skrtel is a bag of nerves.”
“If Villa can stop Philippe Coutinho, they will have a great chance. He’s the man right now. I know they’re talking big money for Raheem Sterling, but I know who I’d be going for.”
Coutinho has started 26 Premier League matches for Brendan Rodgers’ men this season, scoring four goals and adding a further four assists.
His wonderful 2015 form has earned him international recognition with Brazil in recent weeks, certainly no mean feat given the array of attacking talent available to the Samba boys’ boss Dunga.