Ruckman Dawson Simpson has opted for a fresh start after eight injury-plagued seasons with Geelong, signing with Greater Western Sydney as a free agent. 

The Giants sealed the deal on Friday and the 26-year-old will move immediately as an unrestricted free agent, giving the Cats no right to match the offer.

The Cats are pursuing Gold Coast ruckman Zac Smith, so it was unlikely they would have attempted blocked any move from the big man.

Giants football manager Graeme Allan said Simpson would provide valuable support for Shane Mumford, who suffered a season-ending ankle injury in round 11 earlier this year.

"Dawson comes from an excellent football system at Geelong and offers the support for Shane Mumford we’re looking for," Allan said.

"His experience will also be really important for our exciting crop of younger ruckmen who are looking to build on the exposure they gained this year."

GWS won seven of its first 11 games this year when Mumford was at the helm of their ruck division, but after the former Swan went down, it won just four more times.  

Promising young trio Tom Downie, Rory Lobb and Andrew Phillips struggled to fill the massive hole left by Mumford in the second half of 2015.

Simpson, 206cm and 116kg, shapes as a more battle-hardened sidekick for Mumford, but the Giants will be hoping that he can enjoy a better run with his body than he did in his eight years at Geelong.

The former Murray Bushranger played just 28 games at the Cats, having undergone three major back operations in his time at Simonds Stadium.