His nemesis at the US Open last year, Roger Federer had too much for John Millman this time at the Halle Open.
In his first match since March, Kevin Anderson came from behind to beat Cameron Norrie at Queen's.
Second seed Alexander Zverev moved into the Halle Open last 16, but Gael Monfils was an early casualty on day one in Germany.
Andy Murray looked set to retire this year but, as he prepares to return in doubles, Feliciano Lopez believes his quality is still evident.
The Rosmalen Grass Court Championships final saw Adrian Mannarino end his ATP title drought with victory over Jordan Thompson.
Felix Auger-Aliassime was denied a first ATP Tour title by Matteo Berrettini, who won the Stuttgart Open final.
Matteo Berrettini and Felix Auger-Aliassime will meet in the Stuttgart Open final, but the semi-finals are yet to be resolved in Den Bosch
The draw for the Fever-Tree Championships has pitted Andy Murray and Feliciano Lopez against Juan Sebastian Cabal and Robert Farah.
Felix Auger-Aliassime will battle with compatriot Milos Raonic for a place in the final of the Stuttgart Open.
Alexander Zverev is 165 places above Dustin Brown in the rankings, but lost to his compatriot on home soil in Stuttgart.