Ruud run continues in Rio
Ruud, just 18 years of age, won his first ever ATP World Series match against Rogerio Dutra Silva earlier in the week.
After beating Monteiro, only two matches now stand between him and the title.
And if he plays at the same level he played at against Monteiro, anything can happen for the Norwegian prodigy.
Ruud was quite magnificent on Friday. Monteiro is a fine player and he was playing in front of a boisterous home crowd.
However, Ruud was unperturbed. He broke in the first game of the encounter and then closed out the first set with a combination of big serving, clinical work at the net and pure ground strokes from the back of the court.
The second stanza was a far tighter affair as both players held serve to force a tie-break.
In the first set, Ruud illustrated his raw talent. In the second set, he showcased his ability to produce clutch plays.
He was calm and composed under pressure and the claimed the breaker to progress to the semi-finals where Spaniard Pablo Carreño Busta lies in waiting.
In the other semi-final, Dominic Thiem will lock horns with Albert Ramos Viñolas.
After turning professional in 2015, Ruud is a player destined for great things.
In his first ATP Challenger Tour event in Seville last year he came through qualifying and ended up winning the title.
In one year, the teenager jumped from outside the Top 1,000 to the verge of the Top 200.
His father, Christian Ruud, was a Top 50 professional tennis player. He reached a career-high number 39 in the Emirates ATP Rankings and finished his career with 115 tour-level victories.
Asked if he felt pressure to live up to his dad’s lofty standards, Ruud explained there was none of that.
“I have a great relationship with my father,” he said.
“Sometimes in the world of sport it isn’t easy to have such a strong relationship, but for us it’s marvellous.
“We are both very competitive and both love to win at everything.
“We do it with the greatest respect and it’s a healthy rivalry.
“He is an essential part of my team. I don’t feel any pressure that he was a professional player. In fact, it’s the opposite, it has helped me a lot.”