Australian Open Day 9 Tip: Keys can beat weakened Rybakina

• Fritz latest big name to fall in men's draw

• Keys in convincing form

• Sinner to be tested by Rune

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Number four seed Taylor Fritz was the latest big name to exit the men's tournament. While three of his fellow top tenners were defeated by teenagers it was an old timer that told for the Californian as 38-year old Gael Monfils rolled back the years to score an impressive four set win.

It's another contender that has departed from number one seed Jannik Sinner's half of the draw, who remains on course to defend his title. However, his unorthodox fourth round opponent Holger Rune is a player that has troubled Sinner in the past and it's not without the realms of possibility that their latest match will be closer than the odds suggest.

In the women's tournament, Iga Swiatek still looks the player to beat in the bottom half of the draw after her ruthless 6/1 6/0 defeat of Emma Raducanu.

It seemed likely that Swiatek was on a collision course with Elena Rybakina to determine the finalist from their section of the draw but the Kazakhstani has picked up an injury and is facing an in-form Madison Keys that is shining in the performance data.

On Monday it is the Sinner and Rybakina matches that I am placing under the microscope.

Rune's rhythm busting

I am reasonably convinced that Jannik Sinner will defeat Holger Rune in their match. After all Sinner is the player ruling the roost in men's tennis, especially on a hard court.

Sinner has been playing in a low gear this tournament, coasting past all three of his opponents without facing any real pressure. It is not a criticism of his current level, rather he has been utterly comfortable given the bang average opposition he has encountered.

In the fourth round there is the potential for him to be put to work as opponent Holger Rune is showing some good stuff.

Rune is a young player looking to make amends this year for a wayward spell in 2024. The 21-year old has been as high as world number four in 2023, and early signs are he will make a good stab at jumping back up the rankings in 2025.

Sinner has become the best player in the world at controlling play from the baseline. Most players on tour try to emulate his game built on the fundamental principles of strong serving and baseline control. For that reason he is head and shoulders against most opposition who bring an inferior toolkit and nothing to surprise him with.

Holger Rune doesn't fit that mould with his game based on changing the tempo and rhythm of points. He typically follows an emotional rollercoaster in search of inspiration throughout a match with highs and lows in his concentration and intensity.

They are split at two wins apiece and all matches have spanned three sets. This will be their first encounter in the five set format of a Grand Slam.

It is only really the high variety types of players where you place some doubt on Sinner's in-match dominance. Sinner has yet to overwhelm the similarly versatile Carlos Alcaraz, while Rune also has some attributes to challenge him.

Ultimately it is difficult to believe that Sinner will not be steady enough to navigate his way past the mercurial Rune, but if the Dane brings his best to this match he can unsettle Sinner.

Faith in Sinner is high and he is priced a heavy 1/121.08 to defeat a very capable opponent returning to some positive form. He will probably win this match but Rune can make him work for it and I like the chances of backing Rune to find at least an inspired set in this match at 7/52.40.

Rybakina's bad back

At the outset of the tournament I was confident that there would present a moment where it made good sense to oppose Elena Rybakina.

The 2022 Wimbledon champion missed large spells of last season with one injury or another, reappering in time for the WTA Finals in Riyadh at the end of the year.

Her form was rusty then, and at the start of this season the rust was still noticeable in her loss to Iga Swiatek at the United Cup.

She has played a lot of tennis already this season, which followed a vigorous pre-season schedule as demonstrated by her regular social media updates, and it appears the increase in physical intensity is taking its toll.

Rybakina picked up a back injury in her third round victory over Dayana Yastremska, and in her post-match comments she described the issue in a concerned tone.

She said, "It came all of a sudden. I knew it was difficult for me to stay long in the rallies. I wanted to play aggressive, risk a bit more. I'm happy it went my way. I will see my physio and hopefully he does some magic."

According to the data her opponent Madison Keys is playing her best level of tennis since 2019 when she won the biggest title of her career in Cincinnati and was considered a top 10 player.

Keys has hit the ground running in 2025, finding a way to conquer her own injury challenges, and winning the title in Adelaide.

The pair are split at two wins apiece in their head to head, and it feels an opportune moment for the resurgent Keys to face Rybakina.

There is very little to separate these two overall according to longer term data and Rybakina's injury situation combined with Keys form swings this contest in the American's favour. To be offered odds of 2.285/4 on a Keys victory is appealing.

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