Martinez has over the past two years been targeted by Aston Villa and Liverpool but he chose to stay at the DW Stadium.
On Saturday, the Spaniard will take Wigan to Anfield for the first time since being approached in the summer and his club could overtake their hosts in the Premier League.
Wigan chairman Whelan remains delighted with the work of Martinez and is confident the 38-year-old will one day be the boss of one of the continent's best clubs.
Whelan said in the Daily Mirror: "Roberto will be the manager of one of the top three clubs in Europe.
"I signed him from Spain along with Jesus Seba and Isidro Diaz and he played for Wigan Athletic with the other two boys - the Three Amigos they were called.
"That changed our future, because Wigan Athletic then became a team with people playing from Spain who played football from back to front."