Sydney University and National Academy lock Will Skelton has joined the Waratahs.

The towering 20-year-old first caught the attention of Michael Cheika several months ago, when the Sydney-based Academy side was invited for a hit out against Cheika's NSW squad.

One of a number of promising youngsters invited from the club ranks to train with the Waratahs squad for the past three months, Skelton was this week awarded a contract as part of the Extended Playing Squad - following last month's departure of Sam Lane.

At 203cm tall and 135kg, Skelton is one of the most imposing players in the squad.

"I was pretty nervous when I spoke to Michael," he said of his chat with the coach.

"But when he told me they were going to offer me the contract I was stoked.

"I couldn't wipe the smile off my face. Having done pre-season with the boys, it feels great to be a part of the team."

Born in New Zealand to parents of Samoan descent, Will is the cousin of former All Black lock Brad Mika.

Moving to Sydney aged 10, he played junior Rugby League before taking up Rugby Union aged 15 at the Hills Sports High School in Seven Hills, Western Sydney.

After joining Sydney University at the age of 18 and winning a Grand Final with the Colts second XV, he joined the Waratahs Academy in 2011, straight out of school.

After a promising first year, a fractured foot sustained whilst playing for the Sydney-based National Academy side against the Brisbane equivalent in February 2012 forced him to take a year out from playing, confining him to the gym for the remainder of the year.

In great shape and eager to get back into action, Skelton believes the break helped.

"When I came back in the trial match I was pretty hungry to play and I just ripped in.

"Michael said he was pretty happy with that and how I'd worked in the pre-season.

"The Academy was brilliant and the coaches and rest of the boys there were brilliant but I was one of the senior players so this is a big step up."