Action at the Bay Oval, as hosts Northern Districts take on Wellington Firebirds, has kicked off a pivotal round six of the Plunket Shield.

Northern Districts captain Joe Carter won the toss and elected to bat as his side looked to topple last year's Shield winners.

The action is now well underway, with Northern Districts hoping to bounce back after losing a wicket in just the seventh over.

As well as Mount Maunganui there is also action in Invercargill today before a pivotal clash between runaway leaders Canterbury and the resurgent Central Stags tomorrow in Rangiora.

Unbeaten Canterbury has 80 points from four outright wins and a draw heading into the sixth round with a big 32-point lead over Northern Districts, on 48 points at the start of play.

Central also remain a threat. The fourth-placed team face Canterbury twice in the remaining three fixtures affording them the chance to close the gap significantly.

In third spot on 43 points, the Auckland Aces are the only other unbeaten side alongside Canterbury heading into round six. Like Central, the Aces are looking to make up for lost ground after a weather-affected first half of their campaign, prior to Christmas. The Aces and Central Stags suffered a rare washout with no toss made, netting just four points each from November's third round in Nelson.

The Aces have travelled to the deep south to play the injury-hit, fifth-placed Otago Volts. The Volts are without two key players in all-rounder Nathan Smith and strike bowler Jacob Duffy through injury at Invercargill's Queen's Park where an early lunch has been taken while teams wait for the ground to dry off.