Scott McTominay put the Italians ahead in the 31st minute but the Dutch champions swept into a 2-1 lead within seven minutes as Alessandro Buongiorno put the ball into his own net and then Ismael Saibari scored on the counter-attack.
After halftime Man netted twice as PSV took advantage of a frenzied atmosphere at the Philips Stadion to advance to four points from three games, one more than the Serie A champions.
Napoli’s Lorenzo Lucca was sent off 14 minutes from time for dissent to add to the visitors’ woes, although McTominay scored their second in the 86th minute from a corner.
But straight from the restart Couhaib Driouech set up substitute Ricardo Pepi to score with his first kick of the game and within a minute Driouech got one himself with a thumping strike at the end of a series of swift one-touch passes.
The game was played at a high tempo throughout with both sides in an attacking mood and Leonardo Spinazzola’s run down the left wing provided the opening goal for the Italians with his cross being powered home by McTominay.
The Scotland international rose between two defenders at the near post to power home a bullet header.
Own goal as attempted clearence goes awry
But PSV were level within four minutes as veteran Ivan Perisic’s driving cross was helped into his own net by Buongiorno as his attempted clearance went awry.
Then Perisic stole possession as Napoli were on the edge of the PSV area and Guus Til helped it further forward, feeding Saibari to break free and run half the length of the pitch to score.
Mauro Junior’s stubbed cross sat up perfectly for Man to guide home the third goal in the 54th minute and after a sustained period of pressure from PSV, the Romanian international thundered home the fourth from range in the 80th minute.
Three more goals in the final five minutes added to the drama which started before the match when PSV dropped fullback Sergino Dest from the starting lineup after he arrived late for the game, although he did appear as an 85th-minute substitute.
“In the first 15 minutes we had it difficult but after that we took charge and we could have made it eight. But a 6-2 scoreline is more than satisfactory,” PSV midfielder Jerdy Schouten told Ziggo TV.