Chelsea, who last week drew 3-3 with Wolfsburg, had opened the scoring through Scottish striker Erin Cuthbert just after the half-hour mark, only for Juve to draw level minutes later thanks to a perfectly-timed volley from Italy veteran Barbara Bonansea.

But Danish forward Harder, who moved from Wolfsburg to Chelsea for a world record fee in 2020, was first to react to a loose ball in the 69th minute, smashing home past Juve goalkeeper Pauline Peyraud Magnin.

Group A's other match saw German club Wolfsburg hammer Servette from neighbouring Switzerland 5-0, the first of three such one-sided results in Wednesday's four games.

Tabea Wassmuth scored two goals, as Svenja Huth, Dominique Janssen and Joelle Smits all also hit the back of the net.

Canada's Jordyn Huitema hit the first hat-trick of the evening as Paris Saint-Germain hammered Kharkiv 5-0 in Group B.

The 20-year-old Canadian scored her three goals in the opening 17 minutes in an electric start in the French capital.

"It's incredible to be able to put these goals for the team. Just excited that the team has got an other win," the modest Huitema said.

Poland's Paulina Dudek and Lea Khelifi rounded out the scoring for the Parisians against the out-classed Ukrainians.

With seven goals scored and none conceded after two Group B games, PSG will head into their double-header with Real Madrid full of confidence.

"We are super excited to play on this incredible field and incredible stadium" against Real Madrid, Huitema admitted.  

"We have a huge fan base and we like their energy, we were missing the fans for a long time."

Madrid also went two from two, with Caroline Moller scoring a hat-trick of her own in the opening 37 minutes of a 5-0 victory over Iceland's Breidablik.

Olga Carmona and Lorena Navarro added two more in a comprehensive victory.

Reigning champions Barcelona travel to Denmark to take on HB Koge on Thursday, while Arsenal host German rivals Hoffenheim in Group C.

Group D action matches Bayern Munich against Sweden's Hacken, while Lyon entertain Benfica.