Cayless is a New Zealand international

St Helens prop-forward Jason Cayless could miss the Challenge Cup semi-final against holders Leeds because of medial knee ligament damage.

The 28-year-old picked up the injury during Saints' Super League win over Hull KR last Friday.

He is expected to be out for six to eight weeks, making him a doubt for the semi-final on the 26 July.

Chris Flannery also damaged medial ligaments against Hull but is thought to have a good chance of facing Leeds.