Injury-jinxed Shane Watson limped off the field on the opening day of the fourth Ashes Test in yet another setback for the Australian all-rounder on Thursday.
Watson, 32, who has fought an ongoing battle with injuries during his 50-Test career, failed to complete his seventh over late in the middle session and left the Melbourne Cricket Ground.
A Cricket Australia spokesman said: "Shane Watson has some right groin pain and is being assessed by the medical staff on when he can return to the field."
Hamstring and calf injuries have been common for the former vice-captain -- he missed the 2006-07 Ashes campaign with hamstring trouble -- and there has always been a question over how to balance his workload as an all-rounder.
Watson, who has been criticised for a poor conversion rate in Tests with four centuries from 21 half-centuries, hit a quickfire 103 from 108 balls with 11 fours and five sixes in the second innings of the third Ashes Test in Perth before Christmas.