Murray was forced to come back from two sets down to reach the last four, eventually beating Fernando Verdasco 4-6 3-6 6-1 6-4 7-5 while Janowicz secured a comfortable straight-sets victory over fellow Pole Lukasz Kubot.
There has been no British winner at Wimbledon since 1936, and 6'8" Janowicz hopes that the pressure for Murray to end that wait will act as a weight on the Scot's shoulders.
"I hope Andy will feel some kind of pressure," Janowicz said.
"I'm sure he feels some kind of pressure because Great Britain is waiting for the English (sic) champion in Wimbledon.
"So we'll see. I'm not thinking right now about this match. I have still one and a half day to recover, and we will see how it going to be."
By reaching the semi-finals, 22-year-old Janowicz becomes the first Polish player to make the last four of a Grand Slam as well as being the youngest player to reach this stage of Wimbledon since Murray four years ago.