The Colombian international has been a long-term Manchester United target, and has been impressive for Porto so far this season.
And according to reports in Italy, Sir Alex Ferguson could be interested in swapping Hernandez for Rodriguez.
Manchester United's Mexican striker has fallen down the pecking order at Old Trafford following the emergence of Danny Welbeck and the arrival of Robin Van Persie.
The 21-year-old has been linked with a move to Real Madrid, but Ferguson could opt to trade players with Porto instead.
Rodriguez joined the Portuguese club from Atletico Banfield in 2010, and has hit 20 goals in 53 league appearances.
The skilful playmaker is one of the most highly-rated young players in Europe, and already has eight caps for Colombia, attracting interest from Manchester United as well as Serie 'A' giants Juventus and their rivals Inter Milan.
But the 21-year-old midfielder signed a new 5-year contract in June, which is thought to include a buyout clause of €45m, making it unlikely that Manchester United could afford the starlet in a straight cash deal.