Roberts injured his knee in Saturday's road win over Camden and has received intensive treatment over the past two days.

On the plus side, second-rower James Tolhurst has just returned from an injury lay-off and will slot comfortably into the forward pack if Roberts is unavailable.

"Dean is 50/50 at the moment," Shamrocks coach Barry Jones said.

"Hopefully he's right to play, but James is an experienced first-grader and we don't really lose anything if he comes into the side for Dean."

The Rocks have been the competition's hottest side throughout the second round and last tasted defeat in a May 23 home loss to Engadine.

They sputtered through the first six weeks of their 2009 campaign, but the win over Camden lifted them into the top five for the first time this season.

In contrast, Uni were in contention for a top-three finish a month ago, only to lose their last five games and drop to sixth spot.

"It's probably fairly even in terms of which team is under the most pressure," Jones said.

"Uni are playing for their season, but it's the same for us. It's two desperate teams and we're both looking for the points."

Uni wrap up their regular season with Saturday's away game against fourth-placed Engadine, while the Rocks host wooden spooners Vikings in a match which coincides with the Woonona-based club's 40th anniversary celebrations.

"The Vikings game is a big game, but we know we need to beat University before we even think about Saturday," Jones said.

Tonight's match was initially scheduled for July 18 at University Oval but was postponed due to wet weather.

"None of the boys are familiar with Ziems Park but it's probably the same for Uni," Jones said. "We'll get there early to have a look at the ground and get used to the lights, but we won't be changing our game plan just because we're playing at night."

Uni are coming off a 42-22 home loss to premiers Shoalhaven.