Australian Open 2018: Grigor Dimitrov looks to rediscover playing rhythm after loss to Kyle Edmund
Dimitrov lost to Rafael Nadal over five sets in last year's semi-final and has yet to go beyond the last four at a Grand Slam.
Melbourne: Grigor Dimitrov says he needs to rediscover his playing rhythm after the disappointment of crashing out of the Australian Open to British hope Kyle Edmund in the quarter-finals on Tuesday.
The Bulgarian World No 3 was ambushed 6-4, 3-6, 6-3, 6-4 by the 49th-ranked Edmund and again misses out in his 30th Grand Slam tournament.
The 26-year-old lost to Rafael Nadal over five sets in last year's semi-final and has yet to go beyond the last four at a Grand Slam.
"It's hard to hide the disappointment. It's how I feel. It hurts and so it should," Dimitrov told his post-match media conference.
"I need to give myself a couple of days just to relax a little bit and reassess the whole Australian trip.
"I need to be smart the way I'm practising now, not to overdo it again, but in the same time make sure I find my rhythm again, my game itself, the elements when I play.
"That requires quite a bit of work, but I'm certain I'm going to be able to do it and hopefully produce better tennis as the year progresses."
Dimitrov again struggled on serve, giving up seven double faults and being broken five times. Overall he had 43 double-faults in five matches at the tournament.
"Definitely that's one of the things I've struggled with a lot in the past week," he said.
"That's one thing I know if I can turn around, make sure I'm a bit more consistent.
"I felt like some of the matches I was serving pretty much all the matches over 50 percent.
"It's just the winning percentage (42 percent) on the second serve was pretty low, made quite a bit of double-faults. I can only blame myself on that."
Dimitrov said despite his early exit from the year's opening Grand Slam he had nothing to prove.
"In a way, I have nothing to prove to anyone anymore. I'm playing tennis for myself. I've pretty much done, in a way, what everybody thought I would do," he said.
"To me, that's not about it right now. It's really about stepping up my own game, my own belief, my own way of playing.
"For sure once you get to the top, everything becomes more narrow. You have a bigger target on your back. Everybody wants to beat you. So, yeah, it gets harder."
Nadal, a five-time champion in the Spanish capital, saved five of six break points in a challenging opening set as he faced the 76th-ranked Popyrin for the first time.
Nadal, who captured his first Barcelona title as an 18-year-old at the 2005 tournament, will face Pablo Carreno Busta in Saturday's semi-finals.
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The 28th-ranked Karatsev saved 23 of 28 breakpoints to advance to his second final of the year following a 7-5, 4-6, 6-4 victory, gaining a measure of revenge for his defeat by Djokovic in the last four of the Australian Open.