Britain's Johanna Konta needed two hours 38 minutes to beat Kazakhstan's Zarina DiyasGreat Britain v Kazakhstan - Fed Cup World Group II play-offVenue: Copper Box Arena, London Dates: 20-21 AprilCoverage: BBC website will have live text commentaries on all GB matches and you can listen to BBC Radio 5 Live commentary online
Johanna Konta fought back from a set down to beat Zarina Diyas and put Great Britain 1-0 ahead in their Fed Cup play-off against Kazakhstan.
The British number one trailed 5-1 in the first set but went on to win 4-6 6-3 6-2 at London's Copper Box Arena.
If Britain win the best-of-five tie they will earn promotion to World Group II for the first time in 26 years.
British number two Katie Boulter faces Kazakh number one Yulia Putintseva in Saturday's second singles rubber.
The two reverse singles and a doubles match will follow on Sunday (from 12:00 BST).
Konta shows fight in spirited performanceJohanna Konta appealed to the umpire to call for fans to be quieter during points
Konta told BBC Sport she hoped to "feed off the home crowd's energy" before this tie - and that is exactly what she did as the match went on.
But it was the Kazakh world number 107 Diyas who got off to a blistering start - bolstered by constant drumming, trumpet-playing and chants from travelling fans.
An antagonistic tune was played when Konta's volley flew over the baseline as she fell 2-0 down in the opening set and the Briton looked distracted, glancing over at the band seconds before being broken again at 4-1 down.
Konta then smashed her first ace of the match at 5-1 down and went on to claim a comfortable service hold that seemed to spur her and the home crowd on.
She won the next three games and, despite losing the first set, raced to a commanding 5-0 lead in the second.
Diyas, who had lost just one of her 14 previous singles matches in the Fed Cup, responded with resilience of her own - clawing it back to 5-3 before holding off five set points.
But a key moment came when Konta saved two break points in her opening service game of the third set, skipping off at the changeover with a fist-pump towards the crowd.
The Briton could see the finishing line and quickly raced into a 4-1 lead, before Diyas called for a medical timeout for a shoulder issue.
That small break in play did little to quieten the home crowd and Konta responded to the roars of support to break back immediately after dropping serve at 4-2.
It took her two hours and 38 minutes to complete the comeback and the 27-year-old said she hoped her hard-fought victory would give Boulter, 22, the freedom "to do what she can do".
Konta can expect an even tougher rubber on Sunday, though, when she takes on Kazakh world number 38 Putintseva.
