Colin Fleming believes Team GB can beat Belgium this weekend despite the absence of best player Andy Murray.
The world number four was not picked for Braehead as he wants to prepare for the clay court season in Miami.
"It is disappointing for the public and for us when Andy's not in the team," Fleming told BBC Scotland.
"But as a team we're confident we can get a result, and we proved that against Slovakia."
Fleming, alongside doubles partner Ross Hutchins, will be favourites to beat Ruben Bemelmans and David Goffin when they meet on Saturday.
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“Everything's there for us to play our best - which is exactly what we're going to need to do to have a chance”
Before that, on Friday, Josh Goodall will open the tie in singles against the world number 68 Steve Darcis.
Then Dan Evans, who surprisingly won two rubbers in February's defeat of Slovakia, takes on the top Belgian player Olivier Rochus, ranked 59.
Goodall and Evans, ranked 253 and 344 respectively, will swap opponents for Sunday's matches.
"It's the biggest tie we've played since Leon Smith took over as captain, so if we can win it would be a great achievment," said Fleming.
"It would be huge for us individually, as a team and as a tennis nation. We're all keen to make it a reality."
Victory against the Belgians in Scotland would give Smith's men a play-off tie in September to reach the World Group - the top tier of international tennis.
"It's going to be tough. They're favourites for the singles, but hopefully the boys can draw on their experiences against Slovakia," said Fleming.
"But this is going to be even tougher. But I think we're still capable of doing it.
"We have a court surface that suits us, we have players on form and we have the home crowd.
"Everything's there for us to play our best - which is exactly what we're going to need to do to have a chance."
With some impressive Grand Slam performances over the last year, and having just won their second tour title at Delray Beach last month, a degree of expectation is being heaped upon the Fleming and Hutchins partnership.
"We're certainly aware of the fact we're in the team to get a point as doubles specialist.
"I guess it does manage to bring extra pressure, but what we've managed to do recently is just focus on performing as best we can regardless of whether it's a Grand Slam or a 250 tour event.
"That's served us well, so if we can do that on Saturday usually resutls take care of themselves."