Grigor Dimitrov hailed Kyle Edmund as a deserved winner of their Australian Open quarter-final, before suggesting mental fatigue may have played a part in his own underwhelming display.
The third seed at Melbourne Park, Dimitrov was beaten in four sets by Edmund - a player 46 places below him in the ATP rankings.
However, the Bulgarian was not surprised by Edmund's performance, having twice been taken to three sets by the 23-year-old in recent months.
"Kyle deserves all the respect. He deserved to win, simple as that," said Dimitrov.
"He's been working so hard the past months. I've seen that. [I've] played him a couple of times.
"I take full responsibility of my match today. There's no point for me to say what I did wrong because I can sit here and talk about it, but it's all about him right now. He's the winner."
Dimitrov had come through a gruelling clash with Nick Kyrgios to reach the last eight and acknowledged he had struggled to find his best form in Melbourne.
"From day one I was not playing well," he added. "It took me a lot of work to get back to playing a decent match once again.
"It doesn't matter how fit I am, I think also mentally I was just a little bit tired. With each match, you're draining up. Today was just one of those days that I just couldn't find a way. You have days like that.
"I would say all the matches from Brisbane till now, I don't recall an easy match that I played [in] 1 hour 20 [minutes]. Everything was over two hours, over three hours. For sure that takes a bit of beating on the body, considering that my off-season was pretty short. The only time I actually had off was one week.
"Basically I have not stopped playing since November, which is good. I take that as a positive sign, that the body's been healthy."
Asked to rate Edmund's chances of continuing his dream run, Dimitrov replied: "I think once you reach that stage of a grand slam, anything can happen really. It's really how much you want it.
"These kind of opportunities don't always come on the door. So once you have them, try to make the most out of them."
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