Laws handed on-loan Rangers forward Steve McLean his first start for the club, while he reverted to a flat back four with Ireland U21 captain Cliff Byrne drafted in at right-back.
In truth, United were outclassed from the start, as the Stags attacked United with wave after wave of classy play - and they opened the scoring in the eight minute when Liam Lawrence crossed from the right to Rhys Day who had plenty of time to steer his header past Tommy Evans.
The home side could have twice taken the lead before Day's opener, with Evans turning a shot from Iyseden Christie around the post and punching a header from Day over the bar.
They doubled their advantage in the 18th minute when Mendes fired home after being played through by the impressive Christie.
Paul Hayes saw a effort from outside the area tipped over by former Manchester United goalie Kevin Pilkington and Peter Beagrie saw an effort blocked, but in truth the Iron never looked like getting themselves back on the scoresheet in the first half.
Harsh words from manager Laws in the dressing room saw them look mroe composed in the second half, but this soon disappeared as the home side picked up where they had left the first half.
It was 3-0 in the 64th minute when Liam Lawrence fired home a free-kick which went in via a deflection and the underside of the bar.
The goal took the wind out of the Iron sail, and eight minutes later Christie got the goal his play had deserved to make it 4-0 when he pounced on a parry from Evans.
Mansfield inevitably made it five in stoppage time when Mendes set up Lawrence to fire home his second goal of the night with a low shot.
In truth, United were outclassed from the start, as the Stags attacked United with wave after wave of classy play - and they opened the scoring in the eight minute when Liam Lawrence crossed from the right to Rhys Day who had plenty of time to steer his header past Tommy Evans.
The home side could have twice taken the lead before Day's opener, with Evans turning a shot from Iyseden Christie around the post and punching a header from Day over the bar.
They doubled their advantage in the 18th minute when Mendes fired home after being played through by the impressive Christie.
Paul Hayes saw a effort from outside the area tipped over by former Manchester United goalie Kevin Pilkington and Peter Beagrie saw an effort blocked, but in truth the Iron never looked like getting themselves back on the scoresheet in the first half.
Harsh words from manager Laws in the dressing room saw them look mroe composed in the second half, but this soon disappeared as the home side picked up where they had left the first half.
It was 3-0 in the 64th minute when Liam Lawrence fired home a free-kick which went in via a deflection and the underside of the bar.
The goal took the wind out of the Iron sail, and eight minutes later Christie got the goal his play had deserved to make it 4-0 when he pounced on a parry from Evans.
Mansfield inevitably made it five in stoppage time when Mendes set up Lawrence to fire home his second goal of the night with a low shot.