In just 51 minutes on Rod Laver Arena, former world No.1 Angelique Kerber monstered Madison Keys. For those with tickets to centre court for a day of grand slam quarter-final action, you'd hope they turned up on time for the opener.

The case for two-time grand slam champion Kerber being one of the ones to beat in Melbourne was made. Plainly and clearly. After this 6-1, 6-2 victory, fellow semi-finalists Caroline Wozniacki and Elise Mertens probably cast a nervous look from the other half of the draw.

For Keys, there was nowhere to hide. Her capitulation to countrywoman Sloane Stephens in the US Open final barely four months ago, where she lost 6-3, 6-0, was eerily similar.

The 22-year-old, however, said she would not get down in the dumps by her brief quarter-final appearance. The young American has grand slam champion Lindsay Davenport in her corner as coach. They've talked at length about the path it takes to get to the right spot in tennis.

"I'm not going to walk away from this tournament and think it was terrible because I had one bad match," Keys said. "I definitely think I have taken a lot of steps in the right direction and feel good about my game and feel like I'm thinking a lot clearer out there. I think it's just going to take a little bit of time.

"She (Davenport) knows what to say in those moments to calm me down or get me going. I think I have handled a lot of the bigger situations better, and I just need to keep working on that so that I can handle them consistently better."

Kerber's resilience was evident midway through the second set after surprisingly dropping serve. Leading 3-2 the gate was opened for Keys to stage a revival. But the German quickly snuffed it out, needing only one break point chance in the next game to jump back out to a two-game break. It was effectively game, set and match.

The stats were damning for the American and glowing for Kerber. Both players managed 13 winners but 25 unforced errors came from the racquet of Keys, while Kerber committed just seven.

Afterwards the German said she was entirely focused on her own performance. "I was actually just playing my game. Not thinking about errors and winners. Staying in the moment," Kerber said on-court.

"Every game was close in the second set."

Kerber regaining her composure after a year to forget in 2017 has become a common theme at this first major.

She later reflected more on her happy persona.

"I just try to enjoy myself again on court. I know that I was working hard in the off-season, and I know that I can play good matches. I know that I can win close matches and also, yeah, going out there and playing good in the bigger tournaments," she said.

"I just try to find the feeling back that I had, like, 2016 and just enjoying my time. I mean, on and off court, I think this is, for me, it's really important to just have a good time off court.

"I had a tough last year, so that's why I think that I'm just looking forward and I'm proud how I get through all the last weeks and being in the semis again in a grand slam. So I'm feeling good."

Kerber will now play Simona Halep in the semi-finals.