Hernandez goal helps see off United
Hernandez played the first half for his old club and the second for his new side, and made an immediate impact as he netted after just eight minutes, to the delight of the crowd at the new Estadio Omnilife.
Chris Smalling, another United new boy, levelled two minutes later but Adolfo Bautista re-established the lead for the hosts after 38 minutes and Hector Reynoso made it 3-1 just before the hour mark, before Nani pulled one back in the 79th minute.
Hernandez, who has been given a hero's reception on his return to Mexico, was the centre of attention from the start and was given a standing ovation when his name was read out.
He rewarded the fans who had come to cheer him by becoming the first player to score at Chivas' new stadium, striking left-footed first time from Bautista's chest-down to send it into the bottom right corner. But just two minutes later, Smalling rose at a corner to head the ball home and draw United level with his first goal for the club.
United's players had surely been told to go easy on their new team-mate but they were not entirely reverent, as John O'Shea showed when he fouled Hernandez in midfield.
Fabio had an effort well saved by Luis Michel after 23 minutes, but on the whole it was the Mexicans who were playing the better football, and they went ahead when Alberto Medina's centre was played Reynoso to Bautista who fired home with his right foot.
Paul Scholes ensured his own little bit of history five minutes before the break as, fittingly, he picked up the first booking in the life of the new stadium.
Hernandez swapped teams at half-time, replacing Dimitar Berbatov in the United line-up, but he could do nothing to improve their fortunes as Reynoso headed home from Michel Vazquez's corner. Nani did pull one back late on after good work from Tom Cleverley, but there was still time for Juan Antonio Ocampo to hit the post.