Daniil Medvedev lost a second final in two weeks as he fell to a straight-sets defeat to Hubert Hurkacz at the Halle Open on Sunday.
The world number one struggled to get going and repeatedly took his anger out on coach Gilles Cervara, who stormed out of his seat early in the second set.
Top seed Medvedev had already lost the first set 6-1 by that point and only fared slightly better in the second, which ended 6-4 in Hurkacz's favour.
Hurkacz has now won five ATP Tour titles, with this his first on grass, while Medvedev remains stuck on 13 having lost all three finals he has competed in this season.
The most recent of those losses came at the hands of world number 106 Tim van Rijthoven last week, but Medvedev had not dropped a set en route to Sunday's clash in Halle.
Indeed, Medvedev was 14-2 on grass since a first-round exit at Halle last year, yet Hurkacz broke the Russian's first two service games and eased into a 5-0 lead.
Having successfully served out the opener, Hurkacz – who beat the same opponent in this year's Miami Masters – again broke Medvedev in the first game of the second set.
Medvedev took aim at his coach at that point, with Cervara then spotted leaving the stands and failing to return for the remaining nine games, which went the way of the serve.
After easily navigating his way past Medvedev in a match lasting just over an hour, fifth seed Hurkacz becomes the seventh male player in the Open Era to win his first five career finals.