Sydney - Wycliff Palu has given NSW a further boost ahead of the Vodacom Super Rugby clash with the Chiefs on Friday, by extending his contract with the Waratahs.

Palu as well as lock Dean Mumm both decided to lengthen their current deals for a further 12 months, keeping them in NSW and Australian Rugby for the 2012 season.

Despite spending nearly the entirety of last season on the injury list, Palu has proven himself as one of the most destructive No 8s in the country - and his re-signing is a welcomed relief for NSW.

Wallabies utility Adam Ashley-Cooper announced on Tuesday he would also join the Waratahs for the 2012 season after parting ways with the Brumbies.

Waratahs coach Chris Hickey said the signatures of Palu and Mumm were crucial, with NSW now more than two-thirds of the way to completing its roster for next year.

"Cliffy and Dean are two of the most experienced players in the squad and keeping them here for another year is exciting," said Hickey.

"Both players have an enormous impact on and off the field and are greatly respected by the management and playing group.

"Now that they have their next twelve months sorted I'm sure they will both be looking forward to getting on with the 2011 season and Friday's match against the Chiefs at the SFS."

Palu made his state debut against Samoa in 2003 before playing his first Super Rugby match in 2005. The following year he made his Test debut against England.

The powerful No 8 was voted the Players Player in 2008 to receive the Matthew Burke Cup, and then became the first player to win the award twice when he backed up to claim the trophy again in 2009.

A knee injury suffered midway through the Super 14 ended Palu's 2010 season, and he played his first match of 2011 two weeks ago against the Cheetahs.

Dean Mumm made his state debut in 2004 on the Waratahs Development Tour of Argentina. Since then he has gone on to amass 69 state caps, and after making his Super 14 debut in 2007, Mumm has earned 57 Super Rugby caps.

Primarily a lock but also used as a flanker at international level, Mumm has appeared in 32 Tests since making his Wallaby debut against Ireland in 2008.