BLUES turned in another workman-like performance with a second half display of immense importance, as the race for the championship reaches its final stages.
The opening half produced little in the way of clear-cut chances, although the home side were denied by the post midway through the half.
Leek had been restricted to a number of half-chances in the first 45 minutes – but all that changed in the second half following the introduction of new signing Ben Mills, who replaced the unfortunate Niall MaGuire nine minutes after the break.
Within two minutes of Mills taking the field, Tim Grice opened the scoring with a well-taken header and from then on, there was only going to be one winner.
Mills made his presence felt and went on to net a hat-trick of headers in a devastating 12-minute spell towards the end of the game.
Blues boss Lee Casswell said: "It's always difficult against sides scrapping for survival with 10 men behind the ball but we came away with a 4-0 win.
"Tim Grice was on target again, his fourth in as many games, and they couldn't handle Ben Mills when he came on.
"We emphasised at half time we had to be patient because in the first half, there were too many balls played back rather than opening them up.
"It was a good team effort by all the players but Dan Shelley got in some great positions and is now back in the groove.
"I was very pleased to see so many Leek faces behind the goal at the game – their support was tremendous and was appreciated by all the management team and the players.
"Mills' contribution last Tuesday and at Brigg on Saturday was immense and leaves us with some big decisions to make – we've got to make sure we get our team selection right over the remaining games."
Casswell added: "I would publicly like to thank Jamie Cullerton for all the hard work he has done on behalf of the squad this season.
"He has been busy attracting new money, watching games and, more recently, doing a deal with our coach company to make sure our pre-match preparations are spot on – his contribution has been part of our success to date."
Casswell went into the match naming the same side for the last four games while his opposite number was forced to make six changes to the side that lost 4-1 at Leek just two weeks ago,
Leek withstood some early Brigg pressure and in the fourth minute, Jordan Johnson put in a good run – but his shot failed to trouble the keeper.
This pattern continued, with chance after chance going begging.
Blues kicked off the second half on the attack and in the 46th minute, Jordan played the ball wide to Johnston, who crossed into the six-yard box, causing panic, before the ball was cleared.
Four minutes later, Jordan went on a surging run across the Brigg half before playing a reversed ball to Grice at the back post but once again Turner only managed to claim at the second time of asking.
MaGuire fired straight at the keeper in the 52nd minute and then Blues had to defend a quick break by Brigg but William Peers failed to find the target.
Enter Mills! Blues went on to take the lead in the 56th minute when the ball was worked wide to Johnston and he crossed into the box, where it skimmed off the head of Brigg's Scott Hellewell and Grice was on hand at the back post to steer a header into the back of the net.
Blues almost increased their lead on the hour, when Mills played the ball wide and Dan Smith crossed for Grice – but his shot was turned round by the keeper. Just two minutes later, the home defence had their work cut out blocking three shots inside the box.
Leek won a corner in the 68th minute but Mills' shot was deflected. Two minutes later, Johnston took on the defence before pulling the ball back for Ant Danylyk – but the latter shot over from 25-yards out.
However, Leek increased their lead in the 72nd minute when Bell played the ball back to Dicker and he picked out the run of Johnston, who crossed to the far post, where Mills got up to finish with a classic downward header.
Jordan and Mills then combined to set up Dan Shelley in the 74th minute but he failed to keep his shot down.
Blues stretched their lead even further in the 79th minute when Shelley drove in a free kick from wide on the right and up popped Mills to power a header home from close range.
Five minutes later, Mills was celebrating his hat-trick when he got on the end of another corner from Bell to nod home Leek's fourth goal and the points were secure.