Tim Henman says the state of British men's tennis is "embarrassing" and that unless Andy Murray plays GB have little chance of progressing in the Davis Cup.
World number two Murray has pledged to make himself available to face Croatia in September's World Group play-off.
"The signs are he will probably play against Croatia so I fancy their chances," said Henman.
But he added: "The fact we haven't got anyone else inside the top 200 in the world is still a bit embarrassing."
Dan Evans starred in the win over Russia at the weekend but he is currently ranked down at 324th in the world and Henman said the underachieving 22-year-old needs to "give 100% to his job" if he is to maximise his talent.
Evans shocked Evgeny Donskoy 6-4 6-4 6-1 as Britain clinched a place in the world group play-offs thanks to a historic 3-2 victory over Russia in Coventry.
But Evans admitted in an interview that he lacks consistency because "I don't train hard enough and don't work hard enough day in day out".
Evans is widely considered to have the talent to get inside the top 100 in the word rankings but former world number four Henman is frustrated by the 22-year-old's attitude.
"He's a pretty good athlete but he lets himself down mentally," Henman, speaking at the launch of the Aegon Classic, which will be staged at Edgbaston Priory in Birmingham from 9-16 June, told BBC Sport.
Asked whether he could see Evans break into the world's top 100, Henman said: "Not if he carries on with the attitude he has had.
"There's far better players than him in the world. But he has to maximise his potential.
"What is his potential? I don't know, he doesn't know.
"He has to find that out and the only way he can do that is if he commits, he works and gives 100% to his job."
The next best placed British men's player in the world rankings after Murray is James Ward in 217th.
Jamie Baker is 235th, Josh Goodall is 282nd and Alex Bogdanovic is 19 places lower. Edward Corrie is 326th, Daniel Smethurst 371st and Joshua Milton 379th.
"It's fantastic that Andy is number two in the world," Henman added.
"He's doing what he's doing and he's a great example for the groups behind him."
On Great Britain's Davis Cup chances against Croatia, Henman said: "It would have been nice to have had a home tie on back of the win over Russia - I guess it depends a little bit on whether Andy Murray plays.
"But when you look at the Davis Cup and the big picture, those are the easy weeks playing in front of your home crowd.
"It's about whether those other guys can produce that for the other 48 weeks of the year. They have got to do it more often and then you can talk about them improving their rankings."