Johanna Konta had put Great Britain 1-0 up by coming from behind to beat Kazakhstan's Zarina DiyasGreat Britain v Kazakhstan - Fed Cup World Group II play-offVenue: Copper Box Arena, London Dates: 20-21 AprilCoverage: Live commentary on BBC Radio 5 Live and live text commentary on BBC website
Great Britain are level at 1-1 with Kazakhstan after the opening day of their Fed Cup play-off following victory for Johanna Konta and defeat for Katie Boulter.
Boulter lost 6-3 2-6 6-6 (6-8) to Kazakh number one Yulia Putintseva despite having three match points.
Earlier, British number one Konta beat Zarina Diyas 4-6 6-3 6-2.
Britain are seeking promotion to World Group II for the first time in 26 years in the best-of-five tie in London.
The two reverse singles and a doubles match are taking place from 12:00 BST on Sunday.
Heartbreak for Boulter after 'cruel' defeat GB captain Anne Keothavong (left) comforted Boulter after the defeat
Katie Boulter's Fed Cup debut in February was impressive and she started off in much the same way here at London's Copper Box Arena.
The 22-year-old was the underdog against world number 38 Putintseva but she held her nerve to fight off deuce at 3-3 in the first set, before breaking in the following game.
That brought a reaction from the home crowd and Boulter used every opportunity to work them up - roaring in celebration after firing a backhand down the line during a service hold to move 5-3 up.
She was fearless in her play and full of confidence after breaking for a second time and taking the first set - silencing the Kazakh band of trumpets and trombones and taking advantage of an out-of-sorts Putintseva.
The Kazakh number one re-grouped to break twice to go 2-1 up in the second set and her pressure took its toll on Boulter, who took a lengthy medical time-out.
Putintseva marched on to claim a comfortable second set but Boulter's resurgence returned as she won the opening four games in the decider and showed no signs of injury.
The Briton was pegged back, though, with Putintseva using all her experience and skill to force a tie-break after breaking back twice and holding off match point in the final game of the third set.
Boulter had a further two match points saved in the tie-break - at 6-4 and 6-5 on her serve - as Putintseva's risky baseline strokes paid off.
The British number two was comforted in her chair by captain Keothavong after she impressed yet again on the Fed Cup stage but to no avail this time.
"She gave everything she had, that's all you can ask," Keothavong said.
"At times she was struggling but she battled and put herself in that position. Sport can be cruel."
Boulter will have to recover quickly as she is scheduled to take on Diyas in what could be the deciding singles rubber on Sunday.
"Of course a loss like that is going to hurt her," Keothavong said. "But she knows she has got to come out again and we'll do everything possible to get her to her best and to be ready, we've got ice baths and trainers ready."
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 she got Britain off to a winning start.
But Kazakh world number 107 Diyas was bolstered by constant drumming, trumpet-playing and chants from the travelling fans as she started brightly.
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 Konta two hours and 38 minutes to complete the comeback but Sunday's opponent Putintseva will not have fared any better from her gruelling match with Boulter.
