Javier Hernandez did not have to leave Mexico to know all about the rivalry between England's two most successful clubs.
uite apart from the unease at Patrice Evra's first meeting with Luis Suarez since the racism row erupted in October, encounters between the clubs who together boast 37 league titles and eight European Cups are rarely serene affairs.
It is the kind of showdown that resonates far beyond the heartland of north-west England, where the rivalry initially emerged.
"I have learned a lot about the rivalry between Manchester United and Liverpool,'' said Hernandez.
"In Mexico we know a lot about this already. All over the world they know about the history of both teams, with so many titles in the Premier League and the European Cup. It is a very important rivalry.
"But when I came here I felt different. I learned a little bit more.
"We work just the same as we do for every game. But in the back of your mind, you know it is Liverpool and it doesn't matter where we are in the league."
After scoring 20 times in an incredible debut season, Hernandez has found life much tougher this time around.
He suffered concussion during pre-season and then a couple of niggling problems that restricted his appearances.
However, goals in successive matches against Stoke and Chelsea, the equaliser in a six-goal classic at Stamford Bridge, has taken his tally to eight, which is only three down on his total at the same time last year.
As ever, Hernandez prefers to share the praise.
Yet even he accepts his latest goal could turn out to be crucial.
"The goals give me a lot of confidence and a lot of motivation to keep working and improving,'' he said.
"But my focus is on the team. I don't care if I score or not.
"My goal at Chelsea was very important. We had been losing 3-0, so it was a great comeback.
"That point could change the title."
The fight with Manchester City and Tottenham looks set to continue for a good while yet, as does Ryan Giggs, who has just signed another contract at the age of 38 and who sets the benchmark for Hernandez and his team-mates to match.
"Why not?" he said, when asked if he could envisage being a United player at the same age.
"Ryan is a legend here and a very good example for football players all over the world, not only at this club."