British number one Jack Draper has pulled out of this week’s Shanghai Masters through injury.

The 22-year-old retired from his quarter-final clash against France’s Ugo Humbert at the Japan Open on Sunday.

Draper required treatment on an abdominal problem and, after trying to continue, had to call it a day at 7-5 2-1 down.

Draper’s camp say he does not yet know the extent of the injury but feels the turnaround from Tokyo to Shanghai is too quick.

The Japan Open was Draper’s first ATP tournament since he reached the semi-finals of the US Open earlier this month.

The world number 20 played for Great Britain in the Davis Cup a few days later but lost both of his matches.

Afterwards, Draper complained that the current tennis schedule is too busy.

“It’s a mental calendar,” he said. “There’s literally no break. It’s really mentally and physically challenging.”

Draper had a first-round bye in Shanghai and would have faced either Hugo Gaston or Jaume Munar in round two.

Novak Djokovic, Carlos Alcaraz and world number one Jannik Sinner are in the draw.

On Monday Alcaraz beat Karen Khachanov 7-5 6-2 at the China Open and will face another Russian, Daniil Medvedev, in the semi-final.

Sinner, facing the renewed threat of a suspension after the World Anti-Doping Agency appealed against the decision to clear him over two positive tests for a banned substance, reached the other semi-final after a 6-2 7-6 (6) win over Jiri Lehecka.

Humbert is through to the final in Japan after beating Tomas Machac in three sets.

He will meet fellow Frenchman Arthur Fils, who came through two tie-breaks to knock out Danish sixth seed Holger Rune.

At the WTA event in Beijing, former world number one Naomi Osaka beat Katie Volynets 6-3 6-2 to set up an eye-catching fourth-round meeting with fourth seed Coco Gauff.