Bayern thrashed Arsenal at the Emirates 3-1 in the first-leg of their Champions League clash.
"The result speaks volumes," he said.
"Especially in the first half, Bayern put us under huge pressure and played very well.
"We started well after the break and deservedly pulled one back, which is what we said we'd do at half-time.
"But at the end of the day we've lost 3-1. It'll now be very, very difficult for us away from home."