Cronulla have survived an almighty comeback from Penrith to advance to within one game of the NRL grand final with a heart-stopping 21-20 victory.

Down 18-6 after 48 minutes, the Panthers mounted a memorable fightback but fell agonisingly short in front of 19,211 at Allianz Stadium on Friday night.

A 72nd minute field goal to Sharks halfback Chad Townsend proved decisive as rival playmaker Nathan Cleary hooked his attempt to level the contest soon after.

The Sharks will now meet arch-rivals Melbourne at AAMI Park next Friday night in what shapes as a mouth-watering preliminary final.

The Sharks were dealt a big blow when skipper Paul Gallen was taken off with a shoulder problem in the 48th minute, compounding the absence of Josh Dugan (shoulder) and Wade Graham (knee).

The Panthers have been called the cardiac kids this year – on four occasions coming back from a 14-point deficit but the task proved too big on this occasion as their tumultuous season came to a close.

After the Sharks led 18-2 at halftime, the Panthers looked dead and buried against one of the best defensive sides in the competition.

However, the Panthers mounted a comeback after fullback Valentine Holmes committed a massive blunder when he allowed the ball to bounce in-goal and Cleary pounced to narrow the margin to 18-8.

A Townsend penalty goal pushed the scores out to 20-8 to give the Sharks breathing space but Isaah Yeo set up a grandstand finish when he crashed over to reduce the deficit to just six with 13 minutes remaining.

And when James Maloney fired tearaway back-rower Viliame Kikau through a hole, Waqa Blake scored to even it up at 20-20.

The Panthers appeared to be on the charge but Townsend potted his second field goal attempt while Cleary was left to rue his miss from in front of the posts.

Earlier, the Sharks stormed out of the blocks and when Sosaia Feki batted back a Matt Moylan bomb for Holmes to go in under the sticks, at 14-0 they were scoring at just under a point-a-minute.

The Panthers had their chances in the first half but were their own worst enemy with James Maloney and Dallin Watene Zelezniak turning over possession when in prime attacking position.

When Moylan put a retiring veteran Luke Lewis through a giant hole, the Sharks took an 18-0 advantage and looked to be cruising to Melbourne given Penrith only broke their duck through a Maloney penalty seconds before the break.