Hubert Hurkacz revelled in defeating the "the best player in the world" after downing Daniil Medvedev in straight sets to lift the Halle Open title.
Medvedev replaced Novak Djokovic as the world number one last Monday, just a day after the Russian fell to a surprise final defeat against Tim van Rijthoven at the Rosmalen Grass Court Championships.
The 26-year-old followed that up with another final appearance in Halle, where he was convincingly beaten 6-1 6-4 by world number 12 Hurkacz.
That made Hurkacz the seventh male player in the Open Era to win his first five career finals, while Medvedev has lost all three showpieces he has contested in 2022.
The US Open success in September was the last trophy Medvedev lifted, but Hurkacz lavished praise on his opponent after the match on Sunday.
"Daniil is an unbelievable player," said Hurkacz. "He's the best player in the world, so it's very tricky to play him.
"All the right shots went my way at the beginning, so I definitely gained a lot of momentum from that.
"I'm super excited. I've been waiting a little for my first [title] this year. I'm happy to win my first ATP 500 title and of course, on the grass it is very special.
"I was serving pretty good today and got a bit of momentum from the first game.
"I saved a couple of deuces on my service game, and then I managed to break Daniil’s serve so I definitely got a bit of momentum. I'm very happy with the win in front of such a great crowd here."
Medvedev boasted a 14-2 record on grass since a first-round exit at Halle last year before meeting Hurkacz, who came in for praise from the world number one.
"Congrats Hubert, great match today, great week. Congrats to you and your team," he said at the post-match ceremony.
"You guys are super nice. Hopefully a lot more matches to play on the biggest stage. Congrats for a great week and the title."
Medvedev was frustrated throughout the match, repeatedly shouting at coach Gilles Cervara, who stormed out of his seat early in the second set.
While he did not address the topic after the final, Medvedev apologised to the crowd for "not making this match longer and more interesting" and acknowledged he was "not easy to be with on the court" this week.