Britain's Andy Murray began what is likely to be his final Queen's appearance with a gritty win over Australia's Alexei Popyrin.
Former world number one Murray, 37, earned a 6-3 3-6 6-3 victory in his first-round match on Tuesday.
Murray, who is a five-time champion at Queen's, is not expecting to play past the Paris 2024 Olympics as he contemplates where and when he will end his glittering career.
Elsewhere, compatriot Dan Evans had to retire with a knee injury after slipping during his opener against American opponent Brandon Nakashima.
There was better news for British number six Billy Harris, who earned the best win of his career by beating Argentine world number 32 Tomas Martin Etcheverry.
New British number one Jack Draper begins his campaign against Argentina's Mariano Navone later on Tuesday.
Evans, 34, fell at the back of the court in the first game of the deciding third set, letting out a loud cry and immediately signalling he could not continue.
The world number 59 has endured a tough season and looked to be in tears as he sat on his chair.
Having not won on the main ATP Tour since March, Evans played superbly to win the first set 6-4, before Nakashima levelled by taking the second 6-3.
But the British number three's hopes of earning a morale-boosting victory were dashed in the cruellest manner.
On the outside court next door, 29-year-old Harris earned the best win of his career by beating Argentine world number 32 Tomas Martin Etcheverry.
Harris, who only earned his first win on the ATP Tour last year, recorded a 6-4 3-6 6-3 victory in his first-round match.
As a result, he will climb to a career-high ranking inside the top 150 next week.