IT’S THE million-dollar question for Queensland tennis – what shape can Rafael Nadal be in next summer?

World No.1 Nadal announced on Friday that the Brisbane International would be his first tournament for 2019.

But the 17-time Grand Slam winner with the punishing playing style has declined to discuss his strategy for his tournament schedule in late 2018.

The 32-year-old’s Queensland fans will watch how he manages his schedule after Wimbledon after he tried last year to play through a knee injury beyond the gruelling American hardcourt swing in August and September, ultimately compromising his fitness for his Australian tournaments.

The 2018 Brisbane International was the sixth of eight tournaments in a row in 2017 and 2018 from which Nadal either pulled out before the event, or could not complete due to his knee injury.

“My strategy is as always to try to stay healthy and competitive – no secrets,’’ Nadal told The Sunday Mail.

“I’m looking forward to coming back to Brisbane. The field is always strong and the venue is amazing.”

Nadal bypassed the Brisbane International last summer because his knee was not ready for tournament tennis and upon his return, the hardcourt grind of the Australian Open proved too much when he retired in the fifth set of his quarter-final at Rod Laver Arena.

“We know how disappointed Rafa was after a knee injury forced him to miss Brisbane earlier this year – he and his team jumped at the chance to come back again in 2019,” Brisbane tournament director Cameron Pearson said.

The entry by Nadal for the December 30-January 6 tournament is a massive boost for the Queensland Tennis Centre event in its promotion and pre-event sales.

In the two years in which he has entered Brisbane, Nadal has taken a place at a rich Abu Dhabi exhibition in the days before, so it stands to reason he will see the six-man Middle East exhibition again as the place to blow out some competitive cobwebs before flying to Australia.

Nadal, second seed at Wimbledon this week behind world No.2 Roger Federer, is insistent on playing on his least-favoured grass surface.

But he has not played a lead-in tournament on the surface after the wear and tear incurred on the way to an 11th French Open title last month.

“When you get older, you need to adjust a little bit more the efforts and the calendar (schedule), but for me it is difficult to say I don’t play, for example, grass, or I don’t play hardcourt,’’ said Nadal, who last made a Wimbledon quarter-final in 2011.