Australian Open 2018: Roger Federer through but Stan Wawrinka beaten

Federer is seeking his sixth Australian Open title

Roger Federer enjoyed the kinder conditions of the night session as he beat Germany's Jan-Lennard Struff at the Australian Open.

After the temperature earlier neared 40C, second seed Federer saw off Struff 6-4 6-4 7-6 (7-4) in closer to 30C.

The five-time champion goes on to face French 29th seed Richard Gasquet in the third round.

Federer's fellow Swiss Stan Wawrinka was beaten in his second match since returning from knee surgery.

The 2014 champion, seeded ninth, only decided to play in Melbourne on the eve of the tournament and was well below his best as he lost 6-2 6-1 6-4 to Tennys Sandgren of the USA.

"I think the last 12 days was more than what I could have dreamed coming here," Wawrinka said.

"I really came without thinking I will be able to play the first match. That's a big step for me."

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There were no such problems on Rod Laver Arena for Federer despite an impressive performance from Struff, the world number 55.

Federer, 36, broke serve once in each of the first two sets but had to recover from a break down in the third before sealing victory in the tie-break.

Asked if he had requested an evening match, Federer said: "It's not my call, it's [the tournament officials'] call.

"I wouldn't have minded playing during the day because if you want to get to the top, you've got to thrive in all conditions."

Belgian seventh seed David Goffin was knocked out in the second round, going down 1-6 7-6 (7-5) 6-1 7-6 (7-4) to 36-year-old Julien Benneteau, the world number 59.

Julien Benneteau has reached the Australian Open third round on three previous occasions

Six-time champion Novak Djokovic made it through in "brutal" mid-afternoon conditions with a 4-6 6-3 6-1 6-3 win over France's Gael Monfils.

Alexander Zverev, the fourth seed, booked a third-round meeting with Hyeon Chung of South Korea after beating fellow German Peter Gojowczyk 6-1 6-3 4-6 6-3.

Fifth seed Dominic Thiem, 24, recovered from two sets down to beat American Denis Kudla and reach the last 32.

The Austrian lost a tie-break in the opener but fought back to win 6-7 (6-8) 3-6 6-2 6-2 6-3.

In round three Thiem will face France's 26th seed Adrian Mannarino, who beat Czech Jiri Vesely 6-3 7-6 (7-4) 5-7 6-3.

Argentina's Juan Martin del Potro, the 12th seed, took four sets to see off Russian Karen Khachanov 6-4 7-6 (7-4) 6-7 (0-7) 6-4.

American Sam Querrey, the 13th seed, had a surprise exit to world number 80 Marton Fucsovics, going down 6-4 7-6 (8-6) 4-6 6-2 to the Hungarian.

Czech Tomas Berdych, twice a semi-finalist in Melbourne, beat Spain's Guillermo Garcia-Lopez 6-3 2-6 6-2 6-3.