Ruud won 6-3 1-6 6-1 to book his place in the semi-finals.
“It feels good and it means a lot,” said the Norwegian. “This is my first semi-final in a Masters 1000 on hard courts, so that’s a good feeling. I’m very happy to do it here in Miami.”
Ruud continues: “I’ve felt good for the couple weeks I’ve been here practising and the matches have felt very good.”
The 23-year-old said today’s match against Zverev was the “toughest challenge yet” of the tournament.
“I hope that I can take what I’ve learned from my three previous semi-finals and bring it into Friday’s match,” added Ruud.
Ruud will now face Argentina’s Francisco Cerundolo in the last four.
Both players are looking to earn a place in their first Masters 1000 final.