Marlon King scored twice as Gillingham made virtually certain of their First Division status next season.

King, 21 later this month, scored both his goals in the second half as the Gills netted four times for the second week running.

But this was a far more convincing victory than last week's seven-goal thriller against Norwich.

United boss Neil Warnock did not field striker Carl Asaba despite speculation during the week that the former Gillingham favourite, who switched clubs last month, would face his old team-mates for the first time.

Asaba was not at the ground to see his new club handed a comprehensive mauling as Gillingham gained the victory that took them past the 50-point mark for the season.

Referee Eddie Wolstenholme made several mysterious decisions early on which frustrated both players and supporters before Gillingham took a 32nd-minute lead through Iffy Onuora.

Last week's hat-trick hero powerfully headed home Nicky Southall's well-flighted corner.

Two minutes later Paul Shaw should have made it 2-0 but missed badly after King's knock-on.

Peter Ndlovu headed United level three minutes after the break, connecting with Paul Devlin's left-footed cross but within seven minutes King had struck twice.

His first was a great strike high into the roof of the net after Marcus Browning had played him in following Nicky Southall's back heel.

Then King took his tally for the season to 13 with a powerful header from skipper Paul Smith's cross, giving keeper Frank Talia no chance.

Talia replaced injured Simon Tracey against the club where he had a trial spell at the beginning of the season.

He was beaten again by Shaw's 69th-minute effort as he slid the ball home to make it 4-1. It was his first league goal for the club since his £450,000 move from Millwall.

Then Browning nearly made it 5-1 but his 20-yard attempt bounced off the woodwork to safety.

Teams

Gillingham: Bartram, Nosworthy, Hope, Pennock, Patterson, Southall, Smith, Browning, King, Shaw, Onuora (Ipoua 84).

Subs Not Used: Saunders, Rose, James, Browne.

Booked: Onuora.

Goals: Onuora 32, King 55, 58, Shaw 68.

Sheff Utd: Talia, Kozluk, Murphy, Morrison, Curle (Jagielka 84), Uhlenbeek (Thetis 45), Montgomery, Bullock (Suffo 45), Ford, Ndlovu, Devlin.

Subs Not Used: Thomas, Woodward.

Booked: Morrison, Curle.

Goals: Ndlovu 49.

Att: 9,502

Ref: E Wolstenholme (Blackburn).