Lens, still second but with their challenge badly dented, had Salis Abdul Samed shown a straight red card in the 19th minute for a tackle that missed the ball but caught Achraf Hakimi on the ankle.
PSG’s response was swift, the champions seizing the advantage to smash in three goals in a nine-minute spree.
“We must not think that it’s done and dusted,” said coach Christophe Galtier. “
We will need to remain serious and determined to maintain our lead and not give any hope to the teams chasing us.
France striker Mbappe made the breakthrough in the 31st minute when he swivelled and hit a pass from Vitinha in off the post.
The goal made him PSG’s all-time record league scorer, taking his tally to 139 and one more than Edinson Cavani managed.
Vitinha made it 2-0 six minutes later with a long-range screamer that left Lens goalkeeper Brice Samba with no time to react.
Messi then got in on the act in the 40th minute after Mbappe backheeled the Argentine through to fire in at a tight angle and put PSG 3-0 up at the break.
Lens hit back in the second half with a consolation goal from the penalty spot on the hour, Polish winger Przemyslaw Frankowski calmly stepping up to send Gianluigi Donnarumma the wrong way.
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