Last updated on .From the section Scottish Premiership

St Johnstone claimed their biggest Scottish Premiership win of the season with a dominant display against struggling Dundee in the Tayside derby.

Murray Davidson's shot was diverted into the net by Jordan Piggott before Scott Tanser struck the Dundee post with a free-kick.

Chris Kane fired the visitors' second before the break.

Blair Alston netted on the rebound after Kane had been denied before Kane got his second of the match.

Saints move to within two points of seventh-placed Motherwell and are now five clear of Dundee, who are 10th.

As referee Craig Thomson blew the opening whistle heavy rain continued to fall on what was an already sodden surface at Dens Park.

But it was St Johnstone who were to cope much better with the conditions, with Liam Craig's early free-kick testing goalkeeper Elliot Parish.

Dundee were forced into a change when Lewis Spence hobbled off to be replaced by debutant Piggott.

Good build-up play down the left from Alston allowed Kane to send the ball into the danger area. Jason Kerr chested the ball down for Davidson and his sliding effort trickled over the line off the unfortunate Piggott.

This shook the home side into action and Simon Murray and Roarie Deacon combined with the latter having his effort blocked, his rebound going over.

Tanser's free-kick rebounded off the base of the left-hand post but the visiting fans sheltering in the Bob Shankly Stand did not have to wait too long for goal number two.

Dundee defender Josh Meekings tried to usher the ball out of play but Alston nipped in and combined with MacLean before giving Kane the simplest of chances to knock the ball into the net.

The goal was celebrated in fine style and none more so than by manager Tommy Wright, who raced towards the visiting fans with glee.

To their credit, Dundee rallied slightly with Steven Caulker having a header blocked before Murray was sent through on goal only to be stopped by a terrific challenge by Tanser.

Murray, along with the entire Dundee support, were claiming for a penalty but referee Thomson was having none of it.

Alston (far right) capped a fine performance with a goal

There was no let up by Saints as they continued their domination. Alston sent Kane through and, although Parish was able to block, Alston had continued his run and followed up to shoot low into the empty net.

Many of the home fans inside the crowd of 5,336 were making their way towards the exits as the visitors notched number four.

Kane cut in from the left and brushed aside defenders before firing high into the roof of the net.

The home fans that decided to remain in the ground were letting the board and manager Neil McCann know exactly how they felt about their team's performance on the day.

The 605 St Johnstone fans, meanwhile, were chanting "we want five" but had to settled for 4-0 against their fierce rivals.