Newport Wasps' Czech Republic rider Pavel Ondrasik has returned home for treatment to his damaged shoulder and hand.
Ondrasik, from Prague, was hurt in a fall at Somerset last Friday in a Premier Trophy meeting, damaging his left shoulder and right hand.
Tim Stone, Newport promoter, said: "He has flown home to get physiotherapy treatment on his shoulder. "It is easier for him to talk about his injuries in his native language and where he feels comfortable."
If the 28-year-old arrives back in Britain and declares himself fit to ride against Exeter in the Knock-out Cup at Hayley Stadium on Sunday afternoon, then Stone will use rider replacement for his partner Tony Atkin who is recovering from a broken left arm.
Ondrasik, the former Trelawny rider, was brought into the side when Stone dispensed with the services of Dawid Kujawa after one meeting.
l Wasps' home meeting with Exeter on Sunday will now become the first leg of their Knock-out Cup tie following Monday night's postponement because of the weather.
No new date has been agreed for the leg at Exeter, but Exeter are hoping for May 24.
Stone said: "There was a downpour at around 5pm and when we arrived they were pumping water off the track. There was a huge pool on the back straight.
"We walked the track and in some places it was quite firm but slushy in others.
"When the water was pumped off it would probably have taken another hour to move some of the dirt away from the racing line to make it rideable.
"We were all prepared to wait for that but at 7pm another downpour put paid to things."
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