Alexander “asparagus” Zverev kept his quest for a maiden Grand Slam on track with a comprehensive 6-3, 6-3, 6-2 win over Australian wildcard Alex Bolt on Rod Laver Arena Saturday.

The 21-year-old German number four seed and flagbearer for the next generation of young players cruised into the last 16 of the Australian Open for the first time in just 112 minutes.

The tall German, who was pounding down serves at around 220 kph (135 mph), said he had been working hard in the gym with help from trainer Jez Green, who bulked up Andy Murray’s physique and has put on weight in the last couple of year.

Trouble is, no one has noticed, which lead to a hilarious on-court interview with post-match humour specialist Jim Courier.

“I’m disappointed,” he joked. “I’m still the skinny dude on tour, even though I put on about 15 kg.

“When (Jez) started working with Andy, you can actually see he became one of the strongest dudes on tour, whereas I’m still looking like, I don’t know. I have been called asparagus a few times,” he laughed.

This prompted Courier, who is known to bring out the best in interviews after a match, to suggest he start wearing sleeveless vests like Rafael Nadal.

Zverev raised his sleeve in response to show that no one would be scared of his bicep size.

“Look at the that, who is going to be scared of that. When Rafa puts that on it is intimidating, if I put that on, they might start laughing,” he said to peals of laughter from the crowd.

Zverev had almost not made it to third round as he blew a two-set lead against France’s Jeremy Chardy in round two before pulling through in five sets.

He clearly learnt from that experience and after again being two sets ahead, this time he kept his foot on his opponent’s throat.

The 26-year-old Bolt, sporting a Neymar-style “pot noodle” hairstyle, had pulled off the greatest win of his career in beating 29th seed Gilles Simon in the second round.

But the world number 155 was never allowed a chance against the man who won the ATP Tour Finals, beating Roger Federer and Novak Djokovic on consecutive days in the process.

“Obviously I had to return well,” said Zverev. “I did that and played my game. It all worked out well.”

Zverev will meet former world number three and fellow big server Milos Raonic of Canada on Monday for a place in the quarter-finals.

“To be honest I’m not expecting a lot of long rallies,” he said, looking ahead. “We both serve pretty well.”

The young German has a poor record in Slams, only reaching one quarter-final in 14 previous attempts, but should hit the second week in Melbourne fresh and firing after being barely extended by the outclassed Aussie.

With inputs from AFP