Johanna Konta and Heather Watson came from a set down in the final-match decider as Great Britain kept alive their Fed Cup promotion hopes with a dramatic play-off victory over Croatia.

The British pair recorded a 4-6 6-4 6-3 success against Ana Konjuh and Donna Vekic in the doubles after a surprise defeat for Konta left the teams level following the singles matches.

Victory in Tallinn means Anne Keothavong's team progress to a further play-off in April, which could see them reach the competition's second tier - World Group II - for the first time in almost a quarter of a century.

Britain had the perfect start on Saturday and looked like they might wrap up the contest in the singles when Watson began by comfortably beating Vekic in straight sets, 6-2 6-4.

But world number 10 Konta, ranked 27 places higher than her opponent, was beaten 4-6 3-6 by talented 19-year-old Konjuh to send the tie into a winner-takes-all doubles rubber.

Konta and Watson endured the worst possible start to the final match as the Croatians secured a double break to lead 3-0 and, despite some resistance, they eventually lost the first set 6-4.

Australian Open quarter-finalist Konta then caused some consternation by receiving treatment to her left ankle early in the second but she shrugged off the minor problem to help restore parity and force a deciding set.

Konta dropped the opening service game of the the third, double-faulting to give the Croatians an early advantage, but the next three games also went against the serve to leave it tied at 2-2 with the tension mounting.

Watson plays a shot during Great Britain's dramatic play-off against Croatia (Getty)

The British duo then finally put daylight between themselves and their opponents to wrap up victory and continue their quest to gain promotion from Euro/Africa Zone Group I.

Team captain Anne Keothavong was delighted with the battling win.

"I'm absolutely ecstatic," she told lta.org.uk. "It's been a real emotional rollercoaster, but the way the girls performed today and throughout the whole week, I'm just so proud of them.

"It wasn't easy today against Croatia with it coming down to the deciding doubles.

"It was so tight, everyone was on the edge of their seats. But they fought their hearts out and played with so much passion out there.

"I'm so proud of them."