Alexander Zverev lifts lid on secret handshake with partner Sophia Thomalla after win at Australian Open

Alexander Zverev has lifted the lid on his secret handshake ritual with partner Sophia Thomalla after the German won through to the Australian Open semi-finals on Tuesday.

Second-seeded Zverev, chasing an elusive maiden grand slam title, was almost knocked down by, of all things, a feather before he steadied to prevail 7-6 (7-1), 7-6 (7-0), 2-6, 6-1.

WATCH THE VIDEO ABOVE: Zverev explains secret handshake.

While Zverev almost self-imploded over a stray feather and crowd interference, the 27-year-old was all smiles after the match and somewhat embarrassed when he was put on the spot by commentator Jim Courier with a curly question in the on-court interview.

Zverev and Thomalla, a German model, actor and TV presenter, had previously been filmed greeting each other with an orchestrated handshake and kiss in the players’ area, which has become a pre-match ritual.

And Courier couldn’t resist the opportunity to put Zverev on the spot in a hilarious exchange that delighted the crowd.

Courier: “In the player area, there are cameras everywhere, you know that right? You’re aware of that?”

Zverev: “I am now.”

Courier: “You know where I’m going with this ... we’ve been watching you and your partner Sophia, you’ve got something cool going on and I’m going to put something on the screen and embarrass you. What’s this secret handshake all about?”

Zverev: “What are you doing to me? I just played for four hours... I mean, we have been together for three and a half years now. Look, man, you got to understand we are German, this is the coolest version of German that you can be. This is the top of German coolness, it does not go any further than that. We did it, we did it well.”

Courier: “I’ve been married for 14 years, my wife and I don’t have a handshake, we’ve got to get going.”

Zverev will next face either world No.3 Carlos Alcaraz or 10-time champion Novak Djokovic, who play on Tuesday night, in his third Melbourne Park semi-final.

“To be honest, I should have been down two sets to love, he served (for) both of those sets. He played better than me,” Zverev said.

“I was not playing great and I thought he was.

“I somehow won the first set, somehow won the second set, (then) I’m up two sets to love all of a sudden and I only need one more set.

“The fourth set was definitely the best that I’ve played and I’m obviously extremely happy to be back in the semi-finals.”

Tennis’ biggest unfulfilled talent, with two grand slam final losses to his name, Zverev won the first set in a tiebreak, fighting back after Paul served for the set at 6-5.

But with a serving Paul leading the second set 4-2, Zverev had his feathers ruffled - then almost imploded.

On break point, the German was incensed at the chair umpire after someone in the crowd yelled out just as he was about to swing at a ball close to the line - making him believe it had been called out.

No action was taken.

The 27-year-old then dropped the following point and received a code violation for an audible obscenity.

Then, at deuce, the umpire called a let after a feather landed near the ball just as Zverev was about to hit it.

It meant the point was replayed and Paul received another first serve.

Zverev plucked the feather - courtesy of one of the many seagulls in the Rod Laver Arena rafters - from the court and brandished it at the umpire in frustration.

“Buddy, it’s a feather!” Zverev squawked.

“There’s millions of them on the court.”

But rather than implode, the German showed he was no featherweight, proving unflappable as he forced the set to a tiebreak.

Paul, 27, served for the set at 5-3 and earned a set point on Zverev’s serve when leading 5-4, but couldn’t take his chances and was broken.

The German demolished the American 12th seed 7-0 in the tiebreak.

But Paul again recovered, breaking Zverev early in the third set and teeing up three set points on serve at 5-2, and this time converting.

It proved only a brief setback for Zverev, who cruised through the fourth set to claim victory.

- With AAP