The opening day of the Australian Open was rocked by drama as Andrea Petkovic collapsed and had to retire.

The German star was leading leading Irina-Camelia Begu 7-6, 3-4 on Monday when she collapsed to the court in distressing scenes.

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Medical staff immediately rushed to the aid of the World No.63, checking her blood pressure and heart rate.

View photos Andrea Petkovic slumped to the ground. Image: Channel 9 More

Unfortunately she was unable to continue, looking very unsteady on her feet as she shook hands with her opponent and left the court.

Not sure what happened, but Andrea Petkovic is down. They’re taking her pulse and blood pressure. #AusOpen pic.twitter.com/Y9TSt6XazC — Ben Rothenberg (@BenRothenberg) January 14, 2019





“It was heat-related. I had the flu last week,” Petkovic said after the match.

“Probably my body was just weak and it was more just to exhaustion and the temperature.

“But I was cleared by the doctor (to play), I felt fine today, maybe a little weak … I couldn’t work as hard this last week as I wanted to.

“But generally I felt fine and then I felt a little bit in the beginning of the second set my coordination was going off a little bit … with dehydration and the heat, I just hit the wall.”

View photos Andrea Petkovic is escorted from the court after retiring. (Photo by Mark Kolbe/Getty Images) More

The horrible scenes left the Australian Open in shock.

Horrible scenes. Petkovic retires after this collapse https://t.co/u9PThSvP9o — Jon Ralph (@RalphyHeraldSun) January 14, 2019





Petkovic collapses after a rally omg pic.twitter.com/z3ipYJJ89N — Lodo 99 (@lodotennis) January 14, 2019





Petkovic down on court 🙁 Hope she’ll be OK but doesn’t look good. #AusOpen — John (@jt_melb) January 14, 2019





Bad luck for Andrea Petkovic here, halfway through the opening round before struggling and retiring (probably due to extreme weather conditions but we'll have to wait for confirmation). Everytime I see something like this I remember Azarenka leaving #USOpen in a wheelchair… https://t.co/eZZKQCSWSw — Gaspar Ribeiro Lança (@gasparlanca) January 14, 2019





Scary moment on Court 5, where Andrea Petkovic collapsed midway through the second set of her match against Irina-Camelia Begu on a blistering opening day at the Australian Open. Petkovic, who retired from the match, looked like she was having her pulse… https://t.co/swx0sAzGBz — Matt Wilansky (@mattwilansky) January 14, 2019





Oh no what a shame, Petkovic forced to retire 😭😭 pic.twitter.com/UB3THm3C1a — LorenaPopa🕵️‍♀️ 🏆🥖👑 (@popalorena) January 14, 2019





New heat policy in place

The temperature hit 35 in Melbourne on Monday as a new extreme heat policy was used at the Australian Open for the first time.

The new ‘heat stress scale’, based on four factors – air temperature, radiant heat, humidity and wind speed – will allow for extended breaks more often than the previous policy.

However, the roof on Melbourne Park’s three indoor courts will only be closed if conditions are so bad as to suspend play on outside courts.

New rules will allow for a 10-minute break between the second and third sets in women’s singles matches when a 4 (out of 5) is recorded on the HSS prior to or during the first two sets of a match.

Men will get a 10-minute breather after the third set if a 4 is reached.

If the heat stress scale goes to 5, play can be suspended.

Previously, organisers could only activate the extreme heat policy and halt play or close roofs when the temperature exceeded 40 degrees and the Bureau of Meteorology’s wet bulb globe temperature index – which is used to estimate heat stress in humans – hit 32.5.