Ireland scrum-half Murray appeared off the bench in both Melbourne and Sydney, while Farrell also featured for the first time in the latter as the Lions cruised to a 41-16 win.
And Murray admits he was impressed from what he saw from Farrell, pinpointing the 22-year-old as England's danger man.
"He's the focal point of their attack and he's taken a lot of leadership for what they do," he said.
"He's a great kicker of the ball, and his passing game, people might not know too much about it, but on the Lions we got to see it up close and personal, and he has a really wide range of passes and his length of pass is huge so we have to be aware of that as well.
"It's our first away game and it's against a side that's going really well, a side that has experience and is extremely powerful."