The Spurs forward believes that a fixture between his club and the German side belongs in the Champions League.
Son Heung-Min believes that a tie like Tottenham Hotspur against Borussia Dortmund belongs in the Champions League rather than the Europa League, according to quotes from the forward published by the Mirror.
Spurs travel to Germany on Thursday to face the 2013 Champions League runners-up in the first leg of their Europa League last-16 clash.
Both clubs are currently second in their domestic leagues, and Dortmund are rated as one of the favourites to win Europe's second-tier competition after reaching at least the last-16 stage of the more prestigious competition in each of the last three seasons.
Son, who played in the Champions League for Bayer Leverkusen before leaving for White Hart Lane last summer, is adamant that this sort of tie between such competitive teams at the top of two of Europe's biggest domestic leagues is too big for the Europa League.
He said, as quoted by the Mirror: "I believe that the match between BVB and Tottenham has a Champions League level.
"Dortmund are second in Germany, we are in England. I think this game is fun and is still as interesting as many games in the Champions League."
Tottenham have only taken part in the Champions League once in their history, when they reached the quarter-final stage in 2010-11 before being beaten 5-0 on aggregate by Real Madrid.
They would have qualified again after finishing fourth in the Premier League in 2012 were it not for Chelsea winning the European trophy that season, meaning that the Blues re-qualified despite finishing outside the top four.
The first leg of the clash between Spurs and Dortmund at Signal Iduna Park kicks off at 6pm on Thursday.