Jannik Sinner claimed his first title as world number one with victory over Hubert Hurkacz at the Halle Open.
Italy's Sinner won his first Grand Slam at the Australian Open in January and replaced Novak Djokovic at the top of the world rankings earlier in June.
He secured his first grass-court title with a 7-6 (10-8) 7-6 (7-2) victory against Poland's Hurkacz, who he also played doubles with in Germany.
Sinner has lost just three matches this season - falling twice to Carlos Alcaraz at the French Open and Indian Wells, and being beaten by Stefanos Tsitsipas in Monte Carlo.
He will be the top seed at Wimbledon, which begins on 1 July, as he looks to go one step further than his semi-final showing from last year.
"I'm just looking forward to Wimbledon. Last year I made the semis, I played some good tennis, so let's see what's coming this year," the 22-year-old said.
"I'm more confident for sure. Obviously the grass might be a bit different from here and Wimbledon.
"But I have one week now to prepare, so hopefully it's going to be a good tournament.”
Paul becomes American number one with Queen's win
However, Paul's big serve again got him out of trouble and he secured victory on his third match point.
Paul is the first American to win the Queen's title since Sam Querrey in 2010.
In the doubles final, Britain's Neal Skupski and New Zealander Michael Venus came from a set down to beat Russian Karen Khachanov and American Taylor Fritz 4-6 7-6 (7-5) 10-8.