Grigor Dimitrov fears the Nick Kyrgios X-factor as the pair shape up for a fourth-round Australian Open blockbuster tonight.
Seeded third behind only Rafael Nadal and defending champion Roger Federer, Dimitrov arrived at Melbourne Park as the challenger considered most likely to break the duo's year-long domination of men's grand slam tennis.
But after barely surviving the first week, the Bulgarian knows he must raise his game to get past the in-form Kyrgios and keep his hopes alive.
Unbeaten in seven outings in 2017, Kyrgios' victory over Dimitrov in the semifinals of the season-opening Brisbane International taught the world No3 a valuable lesson.
Dimitrov fears Kyrgios can be unplayable at times and knows he must seize any small openings he's presented with at Rod Laver Arena.
"You never know what's going to happen [against Kyrgios]," Dimitrov said.
But the fact the 2017 semifinalist is still alive has Kyrgios on guard.
"I know it's going to be tough," said Australia's last man standing.
• Alexander Zverev blew up at the umpire as he complained about playing in dark conditions on Rod Laver Arena that ultimately sparked an unthinkable implosion.
After going down 4-1 in the fourth set against Korean Hyeong Chung the German exploded about the lights not being turned on at the venue.
"Turn on the lights!" Zverev yelled at the umpire. "I can't see the ball on his serve. You don't see that's dark? It's unbelievable, how do they not turn it on?"
He won the next game to make it 4-2 but his mood didn't improve.
"Four the last four games I've been asking to turn on the lights because it's dark," Zverev said.
The crowd jeered Zverev as he made his displeasure known.
Chung won the fourth set 6-3 to send it to a decider as Zverev's meltdown spiralled out of control.
At one stage he'd lost 13 points in a row, then destroyed a racquet.
It continued until the end of the match as Hyeong defeated a top-10 ranked player for the first time in his career.
He hit Zverev with a fifth set bagel to win 5-7 7-6 2-6 6-3 6-0.
• Austrian fifth seed Dominic Thiem has cruised into the second week with a straight-sets third-round win over France's Adrian Mannarino.
The 24-year-old showed no ill-effects of his five-set scare against American qualifier Denis Kudla on Thursday, backing up with a 6-4 6-2 7-5 victory in two hours and eight minutes yesterday.
• Ashleigh Barty is out after falling victim to the awesome firepower of Japan's Naomi Osaka.
Unseeded Osaka crunched clubbed 12 aces and 24 clean winners past Barty to send Australia's last women's singles hope packing with a crushing 6-4 6-2 third- round defeat yesterday. Osaka's reward is a shot at world No1 Simona Halep for a place in a grand slam quarter-final for the first time in her career.