MELBOURNE, Jan. 22 (Xinhua) -- On day nine of the Australian Open, some of the sport's most crafty veterans battled it out in the quarterfinal stage of the tournament with the next generation of tennis talent.

Nicknamed the 'giant killer' by fans and commentators, 21 year-old American hitter Frances Tiafoe came head-to-head with one of the game's all time greats on Tuesday: Rafael Nadal.

After knocking out the likes of fifth seed Kevin Anderson, 20th seed Grigor Dimitrov and experienced competitor Andreas Seppi, the crowd had high hopes for Tiafoe.

But up against a 17-time Grand Slam champion, the difference in experience became evident and Nadal blasted the youngster off the court in straight sets 6-3, 6-4, 6-2.

Despite 13 Aces, no double faults and a 75 percent first serve rate from Tiafoe, Nadal's precision returns flustered the American challenger and left him struggling to find his rhythm against the Spaniard.

"For me it's very emotional to be back in the semifinals here in Melbourne," Nadal said after the match. "In the past I had some troubles at this event, so to play and be back to that semifinal means everything to me.

"I feel lucky to be where I am, after all the things I went through, to still be competing at this level. That's why I wake up every morning and go to the court or the gym, with the goal to be a better player," he said.

In the day's other men's quarterfinal, experience was no match for 20-year-old Greek sensation Stefanos Tsitsipas, who beat out 22nd seed Roberto Bautista Agut 7-5, 4-6, 6-4, 7-6 (7-2).

Garnering a huge amount of support from Melbourne's local Greek community, Tsitsipas is still riding high after overcoming 20-time Grand Slam winner Roger Federer on Sunday.

"It all feels like a fairytale, almost," Tsitsipas said. "I'm just living the dream, living what I've been working hard for."

"I feel a bit emotional but not too much because no, I worked real hard to get here. At the start of year I said my goal was to reach the semis of a grand slam. When answering this question I thought I was crazy. But no, it is real and it just happened."

In the women's bracket, little-known American competitor Danielle Collins overcame Russia's Anastasia Pavlyuchenkova 2-6, 7-5, 6-1.

While Collins looked to take chances and hit down the line, she found herself behind in the first set due to a number of unforced errors.

"I lost that set pretty quickly," Collins explained. "But what was going through my mind was that I think I had at least two breakpoints that I didn't convert, I had an opportunity I think where I could have maybe put myself in a different situation."

"I think I really got it together in the third set and went out with confidence, you know, kind of cleaned some areas of my game up."

It's been a whirlwind ride for the 25-year-old, who had not won a single Grand Slam match before this year's Australian Open.

"This has all been a really incredible experience," Collins said. "Obviously it's my first time playing main draw here in Australia, so I think that's a little bit new to me. This time last year I was playing a challenger in Newport Beach."

In the day's other women's quarterfinal match-up, two-time Wimbledon champion Petra Kvitova had far too much fire-power for local star Ash Barty, taking the contest in straight sets 6-1, 6-4.

On the back foot for the entire match, the 22-year-old Aussie struggled against the baseline hitting of the Czech.

"I served well, I took the first break and I think from that time I was up, in the second she came back, and she didn't give me anything for free. I really had to fight until the end," Kvitova said.

"Ash has great slice from the backhand, chipping round and mixing up, so I knew I had to be very, very low and hit it as I could to not really give her a chance to play her game."

Out of the sport for around 18 months, Kvitova suffered a severe hand injury at the begining of 2016, when she fought off a knifeman who had broken into her home.

With many fearing the gruesome injury might derail or even end her career, Kvitova reflected on the incident after tonight's match.

"I always wanted to come back and play on the highest level, compete with the best, play the Grand Slams, actually be very deep in the Grand Slam, which is happening. Yeah, it just took me a bit to the tears, but it was happy tears, for sure," she said.

"I think I'm seeing life little bit differently compared to before. I know it's just a sport, it's just tennis."