Two years ago, Britain's Davis Cup opponents included a club coach from Luxembourg who did not have a world ranking and a Hungarian university student who had played two tournaments in three years. When they next compete in September they could find Roger Federer or Rafael Nadal on the other side of the net.

Following Britain's remarkable comeback victory over Russia on Sunday, Leon Smith's team will learn their next opponents on Wednesday, when the winners of the eight Group One second-round matches go into a hat with the eight losers from the World Group first-round ties.

The winners of the eight play-off matches in September – in which home advantage will go to the team who played away the last time the two opponents met – will compete in the World Group next year.

With Switzerland and Spain possible opponents, it is just as well that Andy Murray intends to make himself available. Smith's team, nevertheless, have done without him in their last three ties, their progress a tribute both to the hard work and ability of the players and to the leadership and professionalism of their captain.

Smith, who coached Murray as a junior but never played the game professionally, replaced John Lloyd in 2010 in the wake of a defeat by Lithuania, the most embarrassing result in Britain's 113-year history in the competition. They have won six of their seven ties under Smith – all of them, quite by chance, played on home soil. While Murray's return would give Smith a selection dilemma, in that he would have to drop James Ward or Dan Evans, who performed so well against Russia, the captain is not afraid of such decisions, as he showed when replacing Jamie Baker with Evans last week.

"You need competition," Smith said. "With Andy coming back it creates a lot more momentum. What should be interesting and important now is for the other singles players to make sure they go back to the day job over the coming months, which is arguably more important than Davis Cup, and use this to get momentum going to bring up their ranking."

Smith, who says Judy Murray's role as a mentor has been a major factor in his own development, recalled how some eyebrows had been raised at his appointment. "I was very fortunate to have a good team of people around me," he said.

"That gives you a lot of confidence. Then you've got to focus on the way you want to run the team. I've done that since, creating a good team spirit and preparing as best we can with a lot of analysis on the players."

The thoroughness of Smith's preparation, which included Ross Hutchins taking time out from his cancer treatment to study hours of video footage of the Russian players, was evident in the way that Ward and Evans carried out their game plans against Dmitry Tursunov and Evgeny Donskoy, who were both ranked much higher than the Britons.

"When Andy's said he isn't going to play it's over to the other players to use this as an opportunity," Smith said. "I'm confident we can really use this for the likes of James and Dan to go away, reflect on it, look in the mirror and realise that they are very good tennis players. This will give them a lot of confidence moving forward. What we need to do is be around the guys in the coming weeks to make sure they do kick on."

Davis Cup draw for play-offs

Wednesday's draw for the World Group play-offs will pair each of the eight seeded nations with one of the eight unseeded countries. The play-offs will be staged on the weekend of 13-15 September, with the winners going through to play in the World Group next year.

Seeds: 1 Spain, 2 Austria, 3 Croatia, 4 Switzerland, 5 Germany, 6 Australia, 7 Belgium, 8 Japan

Non-seeds: Brazil, Colombia, Ecuador, Great Britain, Israel, Netherlands, Poland, Ukraine