Van Persie's arrival from Arsenal earlier this month has given Sir Alex Ferguson an enviable array of strikers to select from, with Hernandez, Wayne Rooney, Danny Welbeck and Dimitar Berbatov also at his disposal.
Hernandez has yet to appear this season, and reports have linked the Mexico international with a move away from Old Trafford before the transfer window closes.
However, the 24-year-old is happy to fight for his place.
"The great thing about this club is you know you will get opportunities because we play so many games in different tournaments," Hernandez told the club's official website.
"There is competition for places but you always have that. I had that in youth teams when I was growing up and we have it here now because you need a big squad of players.
"There are only 11 places each week and you need to do your best to get one of those places, but it's great to have that competition because it means every player will have to raise the level of their game.
"The gaffer has the decisions to make, but for me I just focus on doing my best every day in training and in every game so I can help my team-mates get closer to achieving our targets of winning the league and all the competitions we play in."
Hernandez, who endured a fitful second season with the Red Devils, is also looking forward to learning from Van Persie.
He added: "I think in life you never stop learning, no matter what age you are. I try to learn from all my team-mates, but obviously it's great to watch the other strikers in particular.
"They have all helped me a lot and I know I will learn a lot off Robin because he is a world-class striker who has a lot to give to the team and a lot to teach us all.
"I think for people that just love football Robin is like Wazza and other top players, you just need to see them play. Even if you're not a United fan, you should watch players like Robin and Wazza because they are world class.
"Robin is someone I have always enjoyed watching - he did a lot of great things for Arsenal and we want him to do the same for us."
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