Barcelona fans were left in complete shock at the Parc des Princes on Tuesday night. In fact, Paris Saint-Germain's demolition job stunned the majority of Europe.The Catalans were amongst the favourites to win the Champions League this season and yet they were completely blown away by PSG in the first leg of the round of 16 clash.You can probably count the amount of times Lionel Messi, Luis Suarez and Neymar have had off days during the same game over the last three years on one hand.But this was one of those rare occasions and PSG made them pay.While 'MSN' struggled, the likes of Marco Verratti, Julian Draxler and Angel di Maria shone to give the French champions a resounding 4-0 victory.The goals came from Di Maria (2), Draxler and Edinson Cavani to effectively dump Barca out of the tie at the halfway point.Di Maria's brilliant free-kick in the first half set the tone for the evening before he added a second spectacular curling effort after the interval to top off a fine individual performance.His manager Unai Emery was clearly so impressed with how things were going he subbed the Argentine off with half an hour to play.Nevertheless, it was a firm reminder to everyone watching that, on his 29th birthday, Di Maria his back to the sort of form we saw at Real Madrid.In England, the winger's reputation has been tarnished somewhat ever since his spell at Manchester United, where he flattered to deceive for most of his only season in the Premier League.But two years on and the former Madrid star is enjoying his football again in Paris and looked as if he particularly enjoyed getting one over his old La Liga rivals.Di Maria's performance still provoked a big reaction from his former supporters at Old Trafford. Here are some of the best tweets:

Barcelona fans can only hope he isn't in the same rich vein of form when the sides meet for the second leg in three weeks' time.