Fed Cup: Johanna Konta wins after Heather Watson loses to Naomi Osaka
|Japan v Great Britain - Fed Cup World Group II play-off|
|Venue: Bourbon Beans Dome, Miki, Japan Dates: 21-22 April|
|Coverage: Live TV streaming on the BBC Sport website and mobile app, BBC Radio 5 live updates, plus live text commentary on 22 April|
Johanna Konta levelled Great Britain's Fed Cup promotion play-off in Japan after Heather Watson lost the opening match to Naomi Osaka.
Britain, who are bidding to reach the World Group for the first time in 25 years, trailed when Watson was beaten 6-2 6-3 by world number 22 Osaka.
Konta won 6-4 6-2 against Kurumi Nara in Saturday's second singles in Miki.
The best-of-five tie concludes with a doubles rubber and the reverse singles from 04:00 BST on Sunday.
The BBC Sport website will have live coverage of Sunday's matches.
If Britain win, they will be promoted to World Group II - the first time they would have a place among the top 16 teams in the competition since 1993.
Konta and Watson are joined in the British team by doubles specialist Anna Smith and debutant Gabi Taylor.
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Konta comes through tough test
Like Osaka against Watson, Konta had to deal with the pressure of being expected to beat her lower-ranked opponent.
Konta has dropped out of the top 10 and fallen to 23 in the world after a poor run since reaching the Wimbledon semi-finals last year, but her quality and resilience helped her to overcome world number 100 Nara.
She broke Nara's serve in the first game of the match, then saw off three break points in the next game - an early advantage that proved to be crucial.
Nara continued to put the Briton's serve under pressure, not least as she saved three set points before Konta dug deep to edge ahead at the fourth attempt.
In similar fashion to the first set, Konta also broke in the opening game before fending off break points to consolidate the advantage, and then went a double break up for a 3-0 lead.
Nara eventually broke Konta's serve for 3-1 but the 26-year-old regained control to go 5-2 up and then serve out for her fifth win in six meetings with Nara.
"Throughout the whole match she did an incredible job of rising to the occasion and she made it very hard for me," said Konta.
"We will come back stronger on Sunday and try to compete well. Naomi is playing at a very high level this year so I will enjoy playing against an in-form player and do my best out there."
Osaka's quality shines through
Osaka is one of the form players on the WTA Tour this year, having claimed her first major title at Indian Wells last month.
It was always going to be a tough start for Watson, whose ranking has dropped to 77 after struggling for form.
The 25-year-old missed a chance to break the powerful Osaka's serve early in the first set, her Japanese opponent then taking advantage to go 3-1 up and then breaking again to take the set.
Watson had two break points in the first game of the second set, but 20-year-old Osaka produced two aces to see them off and go on to earn a vital hold.
Osaka broke again to take a 3-1 lead and, after fending off two break points for Watson in what proved to be the final game, served out by taking her third match point.
Konta is set to face Osaka, who has lost all three previous meetings with the British number one, in Sunday's opening singles match, with Watson then meeting Nara before what could be a decisive doubles rubber.
"There's plenty to play for on Sunday and we're ready for it," Britain captain Anne Keothavong told BBC Sport.
"I feel the team has prepared as well as we could have done and the team know what to expect - there are no surprises out there. It's a case of who is best out there on the day."
BBC tennis correspondent Russell Fuller
Neither Johanna Konta nor Naomi Osaka fluffed their lines in two competitive, but ultimately relatively straightforward matches.
Cheered on by a small but dedicated group of British fans (many of whom had crossed eight time zones to get here), Konta broke Kurumi Nara four times and fought off a fair amount of pressure on her own serve.
In the opening match, Osaka's power was at times breathtaking as she dealt well with the challenge of leading off her country at the age of just 20.
She will be enjoying the fast court, and much may now depend on her match with Konta on Sunday. Then again, Heather Watson and Nara seem evenly matched and any combination of players could yet contest the doubles if the tie is on the line.