TURIN, Italy -- A year ago, Casper Ruud had just cracked the top 30 in the rankings.
Look at him now.
The eighth and final qualifier for the ATP Finals, the 22-year-old Norwegian has joined top-ranked Novak Djokovic, No. 2 Daniil Medvedev and No. 3 Alexander Zverev in the semifinals of the elite season-ending event.
And he's done so in style.
Ruud showed off aggressive tactics in the decisive tiebreaker and served an ace on his second match point in a 2-6, 7-5, 7-6 (5) victory over Andrey Rublev in his final round-robin match Friday to secure his unexpected spot in the last four.
The fifth-ranked Rublev had beaten Ruud in all four of their previous matches.
"I can thank my arm that I was able to hit an ace on match point, because I was so nervous," Ruud said.
Ruud will next face Medvedev, the US Open champion and defending champion of this event, which is being played in Turin for the first time after 12 years in London.
Djokovic and Zverev will renew their budding rivalry in the other semifinal Saturday.
"Even though I'm the fourth guy, I don't consider myself the fourth-best player in the world," Ruud said. "Tomorrow will be a fun day -- probably the biggest match of my career."
Round-robin play concluded with Djokovic beating British alternate Cameron Norrie 6-2, 6-1 in a mostly meaningless match. Norrie replaced the injured Stefanos Tsitsipas, who is ranked No. 4.
"I played well tonight from the first to the last point," Djokovic said. "That's definitely encouraging for the next match tomorrow, which will be tougher."