Wallabies and Melbourne Rebels back James O'Connor spent Saturday night and Sunday in hospital after injuring his ribs playing against the Waratahs.
O'Connor was accidentally kneed in the ribs by Waratahs five-eighth Berrick Barnes on Saturday and had to leave the field in pain.
O'Connor was in extreme pain following the incident but tried to play on for as long as he could.
Rebels coach Damien Hill revealed that O'Connor was having breathing difficulties after the match and confirmed that the Wallabies utility was kept in hospital on Sunday for further tests.
The Rebels have a bye this coming weekend so O'Connor will have almost two weeks to recover from this injury before they face the Bulls in Melbourne.