​Jannik Sinner’s curtailed 2026 campaign has come at a great cost to the everyday tennis fan, and by the end of the year, it will have been nearly six months since we last saw him play.After winning the Wimbledon final and successfully defending his title, many predicted the Italian would go on to dominate the summer, especially with Carlos Alcaraz still out.After all, moving onto his favoured hard courts, the competition seemed scarce, whilst he only seemed to be growing in stature after his huge Roland Garros disappointment.Alas, that was not to be, and a knee injury that would not go away has left its mark on him and the sport.Toni Nadal, chatting with Italian media this week, has now offered some advice to Jannik Sinner, whilst also revealing his theory for why the world number one suffering from a big injury almost felt inevitable.Toni Nadal has advice for Jannik Sinner after his injury strugglesThe Spaniard began by predicting Sinner would return at the Australian Open, but worried about how such a long period out might impact him mentally.Asked if he had any advice, Nadal suggested: “If he approaches this period with a positive attitude, he’ll eventually get back on the same path he was on before retiring from competition. He finished by winning Wimbledon, which is always a great achievement. He has to keep doing what he was doing.“Will he come back a winner? Just like Alcaraz. When Carlos had the problem in Barcelona, he knew how to wait patiently. Already in the first tournament of his return, the US Open, he came close to achieving a great result, then now he’s won Tokyo. I think the same thing will happen to Sinner. He’s too strong not to get back on the same path.”Then, Nadal actually proposed a theory for why Sinner in particular is so susceptible to injuries like the one he has sustained, before taking aim at the tennis lawmakers.He added: “Sinner is a player who sits very low on his legs, bending them a lot. When you run that fast, every time you stop there’s a constant impact that eventually wears you down. When you play at this speed, there’s always some sudden movement, and that’s how injuries happen.“In any case, tennis should change something because it’s not possible for the best players in the world to get injured simply by playing tennis.Photo by Julian Finney/Getty Images“You can get injured if you take a hit or fall. I say it’s time to slow down, perhaps by using smaller rackets that prevent you from hitting so hard.”Because of the nature of this injury and how long he will be out for, Darren Cahill is now reportedly considering staying with Sinner into 2027, despite having initially planned to part ways after the 2024 season.