A-League leaders Sydney have bolstered their depleted defensive ranks by signing defender Hayden Foxe on a six-week contract.

The Sky Blues were already dealing with several injuries before defender Sebastian Ryall strained knee ligaments in training yesterday and was ruled out for six weeks. Foxe, 32, represented Australia at the 1996 Atlanta and 2000 Sydney Olympic Games and also played for West Ham, Portsmouth and Leeds in England.

He also spent two seasons with Perth Glory between 2007 and 2009 and has been added to the Sydney squad for Saturday's meeting with Perth at ME Bank Stadium. "Hayden is an absolute professional," said Sky Blues assistant coach Tony Popovic.

"He has represented the Socceroos and played in the English Premier League so he brings a wealth of knowledge to the group. We have had a few injuries in the last few weeks, especially in our defensive ranks, so Hayden provides us with another body and a lot of experience."