Learner Tien will advance past Gael Monfils at the US Open and cut short Monfils' farewell narrative. Tien comes in as the American 14th seed who already beat Monfils 6-3, 0-6, 6-3 at the Canadian Open on August 5, and he sits inside the top 20 while Monfils was ranked 347 on August 5. Monfils only…