Galeno scored twice in the 10th and 21st minutes and Otávio made it 3-0 on the stroke of half time.
Mehdi Taremi extended the lead three minutes after the break before Rui Fonte reducing the deficit in the 52nd minute.
Taremi was also denied a sensational goal in the 57th minute when his goal was ruled out by VAR for handball.
The Dragons reduced the gap at the top of the table to five points, the three-way battle for the title with Benfica and Braga well and truly on.