Kylian Mbappe scored a hat-trick and Neymar made his return from a three-month injury lay-off as Paris Saint-Germain began their Ligue 1 title celebrations with a 3-1 win over visitors Monaco on Sunday.

PSG were already confirmed as champions earlier in the day after second-placed Lille could only draw 0-0 with Toulouse, and Thomas Tuchel's men subsequently played with freedom in an emphatic triumph inspired by Mbappe against his old club.

The lethal Mbappe took only 15 minutes to make his mark at the end of a stunning counter-attack and he doubled his tally just before half-time, rounding off another well-worked move.

Neymar – fit again after breaking his foot in January – came on at the interval to a huge cheer, before Mbappe completed his treble in the 55th minute to become the youngest player to score 30 goals in France's top division.

Aleksandr Golovin's late strike proved to be nothing more than a consolation for a Monaco side who still face the threat of relegation.

Monaco's chances took an early blow when they lost goalkeeper Danijel Subasic to an apparent thigh strain, and PSG had the breakthrough soon after – Mbappe collecting Moussa Diaby's pass and finishing into the top-left corner to round off a devastating break.

The former Monaco talisman missed a great chance in the 33rd minute, but he made amends a few moments later, playing a one-two with Dani Alves and neatly finding the bottom-right corner from just inside the area.

PSG introduced Neymar for Layvin Kurzawa at half-time, but still Mbappe led the way, hitting the post after bursting past Kamil Glik in the 52nd minute.

He then grabbed his third, tapping in from close range after Alves raced on to Marco Verratti's pass and squared across the face of goal.

PSG lost Verratti to an injury towards the end and Golovin pulled one back with a tidy finish just inside the box, but the hosts' lead was unassailable and they cruised to victory.

What does it mean? PSG unshackled after confirmation as champions

PSG's form suggested they may have been easing up as they failed to wrap up the title against Strasbourg, Lille and Nantes, losing to the latter two.

But they did not even have to kick a ball on Sunday to finally clinch a second successive Ligue 1 title, appearing more fluid and cohesive than they have in recent weeks.

Monaco, meanwhile, sit four points above the bottom three.

Mbappe the star

There can be little doubt who inspired PSG on Sunday. Mbappe looked in the mood right from the start and his two first-half goals were excellent. The hat-trick clincher was a rather more straightforward finish, but it allowed him to secure a deserved three-goal haul.

Badiashile's bad day

Young centre-back Benoit Badiashile got a taste of what it takes to face the very best at the Parc des Princes. The 18-year-old's positioning was poor in several key moments, such as the third goal, while he made no tackles and just a single interception.

What's next?

There is another title on the line for PSG next Saturday as they face Rennes – who are also Monaco's upcoming opposition a week on Wednesday – in the Coupe de France final, before returning to Ligue 1 action the following Tuesday at Montpellier.