Mgarr lead the standings on 25 points from nine games while Xghajra are third from bottom having only nine points also from nine games.
They were the better outfit during the game and fully deserved the verdict.
The early pressure came from Mgarr as they mounted three actions in a row. Gabriel Vella served Nicholas Abela in the area and the ball was cleared to a corner from his shot.
From a well-taken corner kick by Daniel Law, Xghajra keeper Ethan Gerada saved a header by Gabriel Vella and Abela served Law with a through ball in the area but Gerada foiled him with a timely sortie.
In the 12th minute Mgarr opened the score when Abela served Gabriel Vella with a square pass and he scored with a hard grounder from outside the area.
Hardly a minute later the score became 2-0 when Abela won a loose ball just outside the area and after dribbling past four opponents entered the area and scored with a low shot.
Mgarr scored a third goal in the 16th minute when Luke Vella served Gabriel Vella with a cross from the left flank and he scored with a lobbed ball from the right edge of the area.
In the only action by Xghajra, Owen Sammut served Dejan Viacava with a through ball but Mgarr keeper Ronald Vassallo came out of his charge and kicked the ball up-field.
The pressure from Mgarr was incessant before the break. Abela served Gabriel Vella with a square pass but he missed the upright from outside the area. Near the interval whistle, Gabriel Vella was foiled by Gerada who dived at his feet and smothered the ball.
Eight minutes after the restart Xghajra reduced the gap when they won a free kick in midfield which was taken by Christian Fenech who scored with a rising shot.
The hard-working Abela served Law with a square pass and Gerada saved his effort from outside the area in two attempts.
The score became 4-1 in the 44th minute when Luke Vella pounced on a faulty clearance on the left edge of the area and, after advancing, scored with a hard diagonal grounder.
Mgarr kept pressing and Gerada denied Abela with a diving save to a corner.
In the 58th minute Mgarr scored a fifth goal with a choral move between three players. Law served Luke Vella in the area who then served Daniel Vassallo for the latter to score from close-range.
Xghajra scored a second goal in the 58th minute through Christian Fenech.
Referee: Stefan Pace
Player of the match: Nicholas Abela (Mgarr Utd)