Britain's Liam Broady and Arthur Fery were both beaten in their last-16 ties at the Nottingham Open.
Broady lost 7-6 (7-4) 6-4 to Japan's Sho Shimabukuro, before Fery was beaten 6-4 6-2 by fifth seed Dominik Koepfer.
A minute's silence was held on Centre Court after three people were killed and another three injured in attacks in Nottingham earlier this week.
Two 19-year-old students and a man in his 50s were stabbed to death in the city centre on Tuesday morning.
Shimabukuro, 177th in the world, 26 places below Broady, got the first break in the fifth game, although Broady broke back in the 10th game, but then lost the tie-break.
The pair exchanged breaks of serve at the start of the second set before Shimabukuro moved clear to seal the victory.
Fery, 20, ranked 409th in the world, was up against a player, who, at 95th, is ranked 314 places ahead of him.
The Briton earned his maiden Challenger Tour main-draw victory on Tuesday when he rallied to beat former world number 21 Steve Johnson, but could not repeat that against Koepfer.
The German broke Fery's serve early in both sets with the Briton unable to fight back.
Britain's George Loffhagen, 414th in the rankings, will be hoping to cause a shock against China's Shang Juncheng, 176th in the world, later on Wednesday.
Three-time Grand Slam champion Andy Murray won the Surbiton Trophy last week - his first title on British soil since 2016 - and plays France's Hugo Grenier on Thursday.
If Murray, looking to move up from 44th to get into the top 32 to be seeded for Wimbledon, wins he could face fellow Briton Ryan Peniston or either Denis Kudla of the United States or Switzerland's Dominic Stricker in the quarter-finals.
Watson aims to reach quarter-finals
In the women's event former British number one Heather Watson takes on world number 66 Tatjana Maria of Germany.
Current British number one Katie Boulter and fellow Britons Jodie Burrage and Harriet Dart play their last-16 ties on Thursday.
Boulter, who replaced the injured Emma Raducanu as the top Brit earlier this week, needs to win to have a chance of remaining the highest ranked British player.
She faces Ukrainian lucky loser Daria Snigur, who gained a shock win over French Open semi-finalist and 2022 Nottingham champion Beatriz Haddad Maia in Tuesday's first round.