The majority of the focus in France this weekend is on Sunday's meeting between the two arch-rivals and title challengers at the Stade Velodrome.
However, Lyon produced a timely reminder of their own championship credentials by leapfrogging PSG to the top of the table with a routine triumph at the Stade du Roudourou.
Nabil Fekir opened the scoring in the 26th minute in fortuitous circumstances, as his 25-yard effort was spilled into the net by Guingamp goalkeeper Jonas Lossl before Lyon top scorer Alexandre Lacazette then doubled the lead with a 39th-minute penalty,
The France forward powered a shot into the roof of the net from 12 yards after being awarded what looked to be a soft spot-kick having appeared to clip his own heel following a tussle with Baissama Sankoh.
Guingamp were reduced to 10 men a minute before the interval, Christophe Kerbrat seeing red for a rash challenge on Jordan Ferri.
Clinton N'Jie steered Lyon's third into the bottom-right corner after 61 minutes, with Claudio Beauvue's 80th-minute reply for Guingamp proving nothing more than a consolation.
Lyon are now two points ahead of PSG and four clear of Marseille.
