South Sydney Rabbitohs' bid to catch NRL leaders Melbourne Storm was dented as they slipped to a 39-24 defeat to Cronulla Sharks.

After the Storm's massive 40-4 victory over Brisbane Broncos on Friday, the Rabbitohs needed a win to move back to within four points of the top.

But with just four games remaining in the regular season, their chances of challenging for top spot seem slim following an enthralling clash with the Sharks.

Shaun Johnson was in fine form with the boot as he kicked five conversions and two penalties for the Sharks, while Bronson Xerri helped himself to two tries.

Dane Gagai and Cameron Murray had moved South Sydney to within two points of the home side, but Xerri and Josh Morris put the Sharks - now back in the top eight - in control by the interval, with Briton Nikora's score ensuring Campbell Graham's effort was a consolation.

The Rabbitohs slip to third and could fall to fourth if Sydney Roosters beat Gold Coast Titans on Sunday.

Meanwhile, Newcastle Knight's NRL finals hopes took a blow after a dismal 30-6 defeat to Manly Sea Eagles.

The Knights are perennial strugglers away at Manly, and their poor form at Brookvale Oval continued as the hosts ran riot in the second half.

After going into half-time with an 8-6 lead, Manly capitalised on sloppy Knights defending to go further ahead from Joel Thompson's try.

Martin Taupau inflicted more damage soon after, and with Connor Watson wasting a great chance to haul the visitors back into the contest, Jorge Taufua and Reuben Garrick rounded off a dominant victory.

Elsewhere, Canterbury Bulldogs put distance between themselves and bottom club Gold Coast with a 16-8 win over Penrith Panthers, whose own final chances hang in the balance.