Serena Williams battled a misbehaving serve and scorching heat but stayed cool under pressure in a 7-5 6-4 win over Czech Barbora Strycova to reach the Australian Open quarter-finals yesterday.

Second seed Williams was broken three times in the opening set at Rod Laver Arena and again when coasting to the finish line in the second but shifted up a gear when it counted to close out the match in one hour and 46 minutes.

“I think she’s a really smart player, she can do everything,” said Williams of the hard-running Strycova, who caused a shock at last year’s tournament by dumping third seed Garbine Muguruza out in the third round.

“It’s always good I have something I can improve on and I know I can do better on my serve.”

Williams, bidding to win a record 23rd grand slam title in the professional era, has now notched 10 consecutive quarter-final appearances at the majors, dating back to the 2014 US Open.

Williams came into the tournament with doubts about her fitness after she had only two tour matches of preparation since the US Open, but she is yet to drop a set at Melbourne Park.

The 35-year-old great next faces Johanna Konta. The British ninth seed advanced after she dismantled Ekaterina Makarova 6-1 6-4 in their fourth-round clash.

The 25-year-old Konta, Britain’s last hope in the singles after Andy Murray and Dan Evans were bundled out on Sunday, took 69 minutes to send the Russian packing.

Makarova was no match for Konta’s serve or ground game in the first set as she changed angles and depth of returns that prevented the left-hander from getting any rhythm.

Makarova, who beat sixth seed Dominika Cibulkova in the third round, raced to a 4-1 lead in the second set but Konta rallied to win the next five games and sealed victory on her second match point when the Russian’s forehand sailed over the baseline.

Lucic-Baroni’s wait

Mirjana Lucic-Baroni, of Croatia, could barely contain her joy after continuing her remarkable run in Melbourne to reach her first grand slam quarter-final since the 1999 Wimbledon cham-pionships.

The 34-year-old, who won the Australian Open doubles with Martina Hingis in 1998 at the age of 15, bounced up and down with fists clenched in triumph after dispatching American Jennifer Brady 6-4 6-2 in little over an hour.

Lucic-Baroni’s next opponent will be Czech fifth seed Karolina Pliskova who eliminated Australian Daria Gavrilova 6-3 6-3.