Jannik Sinner admitted to having blood tests done after being unwell during one of his Australian Open matches but gave a positive update about them.
Sinner's chances of defending his Australian Open title looked in jeopardy when he struggled physically in the fourth round against Holger Rune. The ATP world No. 1 left the court for a medical timeout during the match because he felt dizzy and unwell.
Despite those issues, Sinner managed to defeat Rune in four sets. Strong serving during the contest to avoid repeated long rallies was essential to fighting through that battle on the Rod Laver Arena.
In an interview afterward, Sinner admitted to having a bad morning before the match that impacted him throughout the contest against Rune. His resilience to grind through those factors was impressive.
Sinner's body language against Alex de Minaur in the quarterfinal contrasted sharply with the previous round. The Italian moved freely and crushed the home favorite in straight sets to set up a semifinal against Ben Shelton.
Speaking to the media after that resounding victory, Sinner said he got blood tests done after his issues in the match against Rune. Despite not wanting to reveal all the details, the young star confirmed they went well.
"After the match against Holger we made some blood test, you know, some tests. They were all solid, all good. So, you know, sometimes it can happen that you just feel not that well in that day. Today I woke up feeling much, much better."
Sinner had informed his team on the morning of the match against de Minaur that he felt good and was not concerned about stepping onto the court like he was against Rune.
"I told my team straight away that, you know, I'm feeling good tonight. Obviously playing not with the heat helps you, especially when you are not feeling that well."
"But today I felt well already in the morning. I'm still not perfect, but I'm not concerned in couple of days that I should be fine. When I went on court, I felt great. With the adrenaline, it helps a lot."
Sinner's match against Ben Shelton is scheduled for the evening after Novak Djokovic and Alexander Zverev's battle. That might give the 23-year-old some reassurance about not becoming unwell again since the temperatures will be cooler.
The rallies against Shelton are also unlikely to be consistently long because of the American's colossal serve and aggressive groundstrokes from the baseline. Sets involving him are usually decided by a few points.
However, those dynamics do not mean it is an easier matchup for Sinner. If the defending champion is fully fit, facing someone with the ability to avoid consistently getting into rallies is likely to be more challenging.
Sinner's match against de Minaur proved the importance of possessing firepower against him. The Australian is an excellent player, but having no powerful weapon is the most significant reason for his 0-10 head-to-head record against Sinner.