The BVB trainer was disappointed that the referee chose not to dismiss the midfielder for a second bookable offence at Signal Iduna ParkXabi Alonso should have been sent off during Borussia Dortmund's Champions League exit at the hands of Real Madrid, according to Jurgen Klopp.
BVB, who finished runners up last season, won 2-0 on Tuesday thanks to a first-half double from Marco Reus but a 3-0 loss at the Santiago Bernabeu condemned them to a quarter-final elimination at the hands of Carlo Ancelotti's side.
Alonso's persistent fouling in the opening 45 earned him a deserved booking, but Signal Iduna Park supporters were incensed when the Spaniard was not given his marching orders for a foul in the second half on Henrikh Mkhitaryan and Klopp felt their indignation was totally justified.
"I appreciate tremendously Xabi Alonso is a one of the best players in the world," the BVB boss told reporters, "but what he did was a tactical foul that involves yellow card and already had one. It was red-card offence.
"That would probably have complicated things by Real Madrid. But whatever I say will not change anything now.
"We were the better team but only won 2-0 and we're out - that's life."
Real Madrid have reached the semi-final stage for the fourth campaign in a row, although on all three prior occasions they have failed to reach the tournament decider.