Shock 4rth round exits for Federer, Kerber in Australian Open

Day seven of the Australian Open served up a number of high profile exits with some of the biggest names in tennis coming up short in their fourth round clashes on Sunday.

In a battle that pit youth up against experience, young Greek star Stefanos Tsitsipas took out 20-time Grand Slam winner Roger Federer in a tight four-set contest.

Despite losing the first set, the 20-year-old was able to fight his way back and take the next three sets with the match finishing 6-7 (11), 7-6 (3), 7-5, 7-6 (5).

In another surprising result, 21-year-old American Frances Tiafoe was too strong for 20th seed Grigor Dimitrov, upsetting the Bulgarian in a gripping back-and-forth battle 7-5, 7-6 (6), 6-7 (1), 7-5.

Last year's finalist Marin Cilic also ran into problems against Spaniard Roberto Bautista Agut, going down in a marathon five-setter 6-7 (6), 6-3, 6-2, 4-6, 6-4.

17-time Grand Slam champion Rafael Nadal made it look easy against Tomas Berdych, beating the Czech veteran 6-0, 6-1, 7-6 (4) to advance to the quarterfinal for the 11th time in his career.

In the women's bracket, the big names also bowed out with world number two Angelique Kerber getting blasted off the court by little known U.S. competitor Danielle Collins 6-0, 6-2.

Although the 25-year-old had not won a single Grand Slam match in her entire career before the Australian Open, Collins now sees herself in the quarterfinals of this year's tournament.

Another big name to say goodbye to Melbourne was five-time Grand Slam winner Maria Sharapova, who got outworked by local Aussie ace Ash Barty 4-6, 6-1, 6-4.

Czech talent Petra Kvitova managed to buck the trend however, ending the dream run of 17-year-old U.S. teen sensation Amanda Anisimova 6-2, 6-1, while fifth seed and 2017 U.S. Open winner Sloane Stephens was bundled out by Russian world number 42 Anastasia Pavlyuchenkova 6-7 (3), 6-3, 6-3.