Kylian Mbappe says Paris Saint-Germain are well aware of where they have fallen short in the Champions League, though offered a reminder that it is not an easy tournament to win.

Mbappe's first-half double against Juventus on Tuesday ultimately proved enough for PSG to secure a 2-1 win in their opening Group H fixture at Parc des Princes.

PSG were sensational in the first half, with Mbappe converting his two shots – both volleys – to put them into a seemingly commanding position after 22 minutes.

Yet Mbappe's selfishness when he went for goal instead of squaring to Neymar early in the second half, followed by some poor defending and goalkeeping at a corner, allowed Weston McKennie to drag Juve back into the contest.

Gianluigi Donnarumma, who made his second error leading to a goal in six Champions League appearances for PSG, atoned for his part in McKennie's goal with a superb save from Dusan Vlahovic, while Manuel Locatelli saw a goal-bound shot blocked late on.

PSG had their chances to put the game to bed, with Mbappe drilling wide after superb play between Lionel Messi and Neymar, with the latter seeing a wonderful volley saved by Mattia Perin late on.

While PSG failed to live up to the dominant first-half display after the break and allowed Juve back into it to the extent that they finished with a similar shot count (15 to 13) and expected goals (1.5 to 1.1), Mbappe claimed the squad are well aware of areas of improvement.

"There is a small difference between the first and the second half. We know that we have some shortcomings," he said in an interview with RMC Sport. 

"My failure [to make it] 3-0? I missed a lot of goals in my life, I'm going to score a lot and miss a lot. These are facts of the game. It's not by missing that you penalise your team, it's by thinking about the failures.

"We have things to work on, It's normal, it's the Champions League. If it was easy, we would have won it by now."

Mbappe's double took him on to 29 goals in the competition for PSG, one shy of Edinson Cavani's club record.

His sentiment was echoed by team-mate Vitinha, who said: "It's only the beginning, we have to improve. We also saw that we did some good things.

"In the second half, we should have controlled the game better, but it doesn't matter, we shouldn't give too much importance to that. It's up to us to work."