Budding Sharks stars Bronson Xerri and Briton Nikora have orchestrated a stunning Cronulla comeback at PointsBet Stadium, roaring back from 20-6 down to swamp Penrith 24-20.

Both youngsters showed dazzling pace and skill to dismantle Penrith in the second half, with Shaun Johnson brushing off an apparent right hip flexor issue to play a leading role in the comeback.

The brilliant four-try second half by the Sharks was at complete odds with the first, in which Penrith enjoyed a familiar structure with their halves returning to their preferred sides of the field and the forwards rolling through the middle.

That allowed the Panthers to dominate the opening 40 two tries to nil. However the loss of centre Dean Whare to a hamstring strain in the 51st minute forced the Panthers to use Isaah Yeo at centre and the less mobile edge was taken advantage of by the Sharks speedsters.

Penrith put themselves under early pressure with a drop at their own line but survived unscathed. Instead it was a Josh Dugan drop in his own end, under no pressure, that paved the way for the returning Tim Grant to score his first try in Penrith colours since 2011, strolling over off a nice James Maloney pass.

Nathan Cleary made it 12-0 in the 16th minute when he got a handy bounce from an attacking Maloney grubber and he added his third goal of the half in the 20th minute following a penalty in front for 14-0.

There were no further points in the opening half but Johnson looked to have strained his hip making a line break while Nikora picked up a back strain late in the half.

Penrith went close to their third try shortly before the break when Josh Mansour crossed straight after a monster Maloney 40/20 kick. But a poor lead line from Viliame Kikau taking out a defender resulted in an obstruction ruling.

First points of the second half came when the Sharks spread it to the right on a kick return in the 49th minute and Xerri got a chance to show off his blinding speed, easily burning Dallin Watene-Zelezniak in a 65-metre run to the line for his side's first points.

The Sharks dominated field position for the next 10 minutes, winning the battle in the middle of the field, but an early-tackle drop from Scott Sorensen, seconds after being called into the fray, turned the tide back to the Panthers. Centre Waqa Blake cashed in on an overlap soon after.

Nikora, who could barely stand up straight when he left the field at half time, turned in a monumental second half and it was his clean break and perfect chip kick to Townsend to score that reignited the Sharks. The penalty try was awarded due to Townsend being tackled by winger Malakai Watene-Zelezniak before he could grab the ball.

But at 20-12 down the Sharks had all the momentum and Prime Minister Scott Morrison was out of his seat.

Another Nikora break set them back on the attack and after five consecutive sets on the Penrith line Andrew Fifita crashed over to make it a two-point ball game (20-18) with six minutes to play.

The next try seemed almost inevitable as the Sharks rolled upfield with Johnson tormenting Penrith's makeshift left edge in the absence of Whare.

When Xerri sent Dugan over in the 76th minute, the Sharks had claimed the lead for the first time in the match.

Penrith had one further attacking set to try and snatch the win but their last-tackle kick sailed too deep to be easily marked in goal as Cronulla pushed their way into the top-eight while Penrith were left to rue back-to-back losses.