Mark Petchey has no future concerns about tennis superstar Alexander Zverev

Tennis sensation Alexander Zverev hasn't made the best of starts to 2018 , but Mark Petchey still believes he will be a multiple major winner.

The 20-year-old finished 2018 ranked No 4 in the world after a sensational year which saw him claim two Masters 1000 titles with wins in Rome and Montreal.

But Zverev has confessed he has struggled under the weight of pressure on the biggest stage and his Grand Slam form makes for dismal reading.

He fell to surprise South Korean package Hyeon Chung as he failed to make just his second appearance at the fourth round of a major at the Australian Open last month. More worryingly, he's now gone 11 majors without reaching a Grand Slam quarter-final.

Despite guiding Germany into the last eight of the Davis Cup with an impressive victory over Australian Kick Kyrgios in Brisbane, the youngster fell in an upset to qualifying lucky loser Andreas Seppi at the Rotterdam Open on Tuesday.

"I'm not worried at all," Petchey told Sky Sports. "He's still only 20 and he's had a fantastic start to his career. People were writing the same rubbish about [Roger] Federer at one stage, and look at what his career has turned out to be like.

"I have absolutely no doubt that Zverev's going to be a major winner in a multiple way. Once he gets to a certain stage of a Grand Slam it will all fall into place.

"It's all about time and he's got absolutely loads of it on his side. There will be a lot of youngsters out there right now who would be quite happy if they had his career. He wants more and obviously he will be disappointed he couldn't have more in Australia, but it will come."

Mark Petchey was speaking to Sky Sports' Raz Mirza. We will be covering the Rio Open, Dubai Duty Free Tennis Championships, and ATP 500 Acapulco this February through www.skysports.com/tennis as we bring you news, previews, live blogs, reports and expert analysis.