The big-serving Pole had too much for his more experienced opponent, and he admitted that he was surprised to go so far in a Grand Slam tournament.
The 22-year-old told BBC Sport: "I'm just very happy. I didn't think I could so far in a tournament like Wimbledon.
"I really do not have many words to say right now."
The number 24 seed will play either Fernando Verdasco or Andy Murray for a place in the final.