Britain’s Andy Lapthorne is a doubt for the Australian Open quad singles event with a hand and wrist injury.
The world number two in the division, for players with impairments in three or more limbs, has pulled out of warm-up events in Sydney and Melbourne.
He is seeing a specialist in the hope of being fit for the first Grand Slam of the year from 24-27 January.
Lapthorne, 27, won the doubles event last year and was beaten in the singles final by Australian Dylan Alcott.
Meanwhile, British trio Alfie Hewett, Gordon Reid and Lucy Shuker all made winning starts to their campaigns at the Sydney Wheelchair Tennis Open.
Second seed Hewett defeated Australian Ben Weekes 6-4 6-1 while Reid, seeded four, only dropped one game against Japan’s Yoshinobu Fujimoto.
In the women’s singles, Shuker defeated Japan’s Manami Tanaka 6-0 6-3 and will next face another Japanese player – world number one Yui Kamiji.