MELBOURNE, Jan. 18 -- On day four of the Australian Open, one could make the argument that the biggest winners on the day were not the players, but probably the vendors selling ice cream and water bottles.

Scorching weather conditions on Thursday saw temperatures rise above 40 degrees Celsius and as a result many big names struggled.

Up first on centre court was a hit out between former world number one, Maria Sharapova, and 14th seed Anastasija Sevastova.

Although many expected a tight contest, Sharapova cruised to victory and won in straight sets.

"It was warm! And it got warmer as the match went on," an exhausted Sharapova told Xinhua.

"Sometimes when you toss the ball up serve, the sun was a problem, but I liked that we were out there a bit earlier."

For those on a bit later in the day, the stifling heat was brutal.

During his second round match with Novak Djokovic, Frenchman Gael Monfils told the umpire he would "collapse," if he kept enforcing the 25-second rule before each service.

Although Djokovic won the tussle in four sets, the Serbian looked far from his best, missing a number of backhand shots and committing several uncharacteristic double faults.

The biggest shock of day came when 2024 Australian Open champion Stan Wawrinka crashed out in straight sets to world number 97, American Tennys Sandgren.

Wawrinka was suspected to have a knee injury going into the tournament and clutched it throughout the contest.

In other men's matches, 5th seed Dominic Thiem scraped past Denis Kudla in a 5-set thriller.

Big names Juan Martin Del Potro, Tomas Berdych and Alexander Zverev all booked their way to the next stage in 4 sets and for the first time at the Australian Open, South Korean Hyeon Chung made it to the third round with his win over Daniil Medvedev.

However 7th seed David Goffin, was bundled out by Frenchman Julien Benneteau and 13th seed Sam Querrey was also upset by Marton Fucsovics.

Roger Federer on the other hand had no such problems with his German opponent, blasting his way to a straight-set victory over Jan-Lennard Struff.

In the women's bracket, top talent Madison Keys, Simona Halep, Karolina Pliskova and Angelique Kerber all advanced in straight sets, while Caroline Garcia managed to overcome Marketa Vondrousova in three.

Australia's 18th seed Ashleigh Barty also took 3 sets to get past Italian hitter Camila Giorgi, in a late night match that had local Aussie fans ecstatic.

But there was also plenty of upsets.

An unbelievable performance from Hsieh Su-Wei saw her defeat third seed Muguruza Garbine.

While American number 123 in the world Bernarda Pera, knocked out 9th seed Johanna Konta and 16th seed Elena Vesnina lost to in form Japanese player, Naomi Osaka.

Despite the heat, 63,000 fans attended the day's play at Melbourne Park.

MELBOURNE, Jan. 18 -- On day four of the Australian Open, one could make the argument that the biggest winners on the day were not the players, but probably the vendors selling ice cream and water bottles.

Scorching weather conditions on Thursday saw temperatures rise above 40 degrees Celsius and as a result many big names struggled.

Up first on centre court was a hit out between former world number one, Maria Sharapova, and 14th seed Anastasija Sevastova.

Although many expected a tight contest, Sharapova cruised to victory and won in straight sets.

"It was warm! And it got warmer as the match went on," an exhausted Sharapova told Xinhua.

"Sometimes when you toss the ball up serve, the sun was a problem, but I liked that we were out there a bit earlier."

For those on a bit later in the day, the stifling heat was brutal.

During his second round match with Novak Djokovic, Frenchman Gael Monfils told the umpire he would "collapse," if he kept enforcing the 25-second rule before each service.

Although Djokovic won the tussle in four sets, the Serbian looked far from his best, missing a number of backhand shots and committing several uncharacteristic double faults.

The biggest shock of day came when 2024 Australian Open champion Stan Wawrinka crashed out in straight sets to world number 97, American Tennys Sandgren.

Wawrinka was suspected to have a knee injury going into the tournament and clutched it throughout the contest.

In other men's matches, 5th seed Dominic Thiem scraped past Denis Kudla in a 5-set thriller.

Big names Juan Martin Del Potro, Tomas Berdych and Alexander Zverev all booked their way to the next stage in 4 sets and for the first time at the Australian Open, South Korean Hyeon Chung made it to the third round with his win over Daniil Medvedev.

However 7th seed David Goffin, was bundled out by Frenchman Julien Benneteau and 13th seed Sam Querrey was also upset by Marton Fucsovics.

Roger Federer on the other hand had no such problems with his German opponent, blasting his way to a straight-set victory over Jan-Lennard Struff.

In the women's bracket, top talent Madison Keys, Simona Halep, Karolina Pliskova and Angelique Kerber all advanced in straight sets, while Caroline Garcia managed to overcome Marketa Vondrousova in three.

Australia's 18th seed Ashleigh Barty also took 3 sets to get past Italian hitter Camila Giorgi, in a late night match that had local Aussie fans ecstatic.

But there was also plenty of upsets.

An unbelievable performance from Hsieh Su-Wei saw her defeat third seed Muguruza Garbine.

While American number 123 in the world Bernarda Pera, knocked out 9th seed Johanna Konta and 16th seed Elena Vesnina lost to in form Japanese player, Naomi Osaka.

Despite the heat, 63,000 fans attended the day's play at Melbourne Park.