Heather Watson is out of the BNP Paribas Open after a 6-4 6-3 second-round defeat by second seed Agnieszka Radwanska in Indian Wells, California.
Watson, 21, had lost her two previous matches against the Pole, including at Wimbledon in 2012.
But it was an encouraging display and continues her revival after battling to recover from glandular fever last year.
"I'm enjoying 2014, that's for sure - a lot more than 2013," said the British number three, ranked 134 in the world.
Watson struggled with her serve throughout but fought back from 3-0 down to level the first set 4-4 before losing it 6-4.
In the second, Watson was again broken early. This time she never got back on terms, though, as Radwanska's class shone through.
Watson has already won 15 matches this year, only one fewer than she managed in the whole of 2013, when her illness sapped her energy.
And victories in her first three matches at Indian Wells in straight sets, two in qualifying and then against 16-year-old Swiss Belinda Bencic in the first round on Wednesday, will have boosted her confidence.
She will now play in the main draw of the Sony Open in Miami in two weeks' time after being given a wild card.
"For me now going forward, all I can do is go up in the rankings, make points, do well," she said.
"And I feel like since the beginning of the year I'm just improving as every match goes along, and I'm starting to play better and better each tournament.
"I'll go back to Florida and get some good training in before Miami. I'm really looking forward to playing there.
"I have done well there in the past. I love the courts and I'm very motivated."
Watson came out firing against Radwanska, 25, on a sparsely populated Stadium 1, forcing two break points in the opening game. But she fired long on both and Radwanska made her pay by winning that opener and the subsequent two games.
Watson has worked hard on adding more power to her game but it was a perfect drop shot that set up the opportunity for her to claw her way back to 3-2.
The gameplan was to attack and she levelled at 4-4 after another break of serve apiece, but Radwanska showed her quality when it mattered to win the opener.
Watson called coach Diego Veronelli, who linked up with her at the end of last year, on court for a quick chat but his player then made a poor start to the second set, losing the first two games before rallying to get on the board at 2-1.
Thereafter, neither player could hold serve and Watson's frustration was clear as breaks in seven successive games kept her behind in the set. That left Radwanska serving for the match at 5-3 and the Pole at last produced a hold to seal it.
"I knew it was going to be a tough match," said Watson.
"I felt it was a lot different compared to the other times [against Radwanska]. I felt I was right in there. I had my chances, and I didn't feel I played that well. It was actually quite windy in there and I struggled with my serve a bit."