A decision on whether or not Istabraq will race again is likely to be made this week.

The former champion hurdler injured a hock at Cheltenham last week that resulted in him being pulled up.

That discovery has delayed what many thought would be his inevitable retirement but Aidan O'Brien said yesterday: "We will assess how he is doing during the week." He also confirmed he is seriously considering giving Johannesburg a run in a new £50,000 race on the all-weather track at Lingfield on Grand National day (April 6th).

Johannesburg's owner Michael Tabor said last month that the Gladness Stakes was the likely starting point for the colt's season, followed by the Kentucky Derby.

However, a new race on the Polytrack surface at Lingfield appears a more likely option with Kentucky in mind. "I don't know for certain what we will do yet but Lingfield is a definite possibility," O'Brien said.