Roger Federer insists his back is in great condition as he prepares for the Shanghai Masters.
Federer is in the Far East for the penultimate Masters 1000 event of the season.
It is a key period for the Swiss, who is looking to build momentum ahead of the season-ending ATP Finals.
Federer will play in Shanghai, his home event in Basel then potentially the final Masters event in Paris-Bercy before competing against the top eight in the world at the O2.
With plenty of tennis still to play, there are question marks about Federer can come through the final six weeks of a gruelling season without injury troubles.
2019 is set to be Federer busiest since 2015 when he played 74 matches.
But speaking ahead of competing in Shanghai again, Federer said he was confident about his physical condition.
Federer told the ATP: “Sometimes I get a bit of a stiffer back as the season gets longer and the longer I play on the hard courts or the colder the weather gets sometimes. That can be an issue too.
“But I must say I feel great with my back. So I can serve full which is obviously required on a fast hard court.
“I want to be explosive and energetic like I was at the Laver Cup.
“But not subdued like I was at the US Open when I was fighting with my back issue.
“So I was happy to see that the reaction was there and now I’ve just got to manage it the right way here in Shanghai.”
Federer is a popular figure in Shanghai and the 38-year-old is delighted to be back.
He said: “I love being here. It is a great event with a lot of history now for me. It’s a fast court. I think it suits my game well too.
“Of course, when it is fast you better be careful and sharp, especially in best of three.
“The weather has been good, practise been going well. I’ve been busy, arrived here early and I’m ready to go.”