The Frenchman has been magnificent for Die Geissbocke and took his tally to 22 for the campaign by netting a hat-trick in Saturday's 4-2 win over Hertha Berlin.
Modeste's total is good enough for him to currently sit second in the Bundesliga scoring charts, one behind Borussia Dortmund's Pierre-Emerick Aubameyang and a single strike clear of Bayern Munich's Robert Lewandowski.
Horn admits he has been impressed by his colleague this season and believes his exploits are more significant than his rivals due to him being presented with less opportunities.
"What Anthony is doing now is comfortably better than his rivals," he said. "Lewandowski has six or seven chances served on a silver platter every match, but Tony has to make things happen. That is why he is higher in my estimation."