Robben praises gritty Kaiserslautern
But the Netherlands international was nevertheless proud of the way his team disposed of the visitors to reach the last 16 of the German cup competition.
Claudio Pizarro opened the scoring for the Bavarians but then had to wait until the second half before doubling their advantage with Robben grabbing the second.
Pizarro then added a third before the hour mark while the Dutch maestro had the final say towards the end.
However, Robben conceded it was not as comfortable as the scoreline suggested.
"Four-nil sounds easy but it was tough, so I'm proud of the lads. We worked very hard," he said.
Coach Jupp Heynckes agreed that Kaiserslautern were difficult to break down and lauded the resourcefulness of his players.
"You could see my players were utterly determined to make the last 16," the coach said.
"Kaiserslautern put up enormous resistance in the first half. I made a lot of changes, but my team still played as a unit, with plenty of ideas and great discipline."
Rafinha injured himself when making an aerial challenge but the full-back took to Twitter to play down the incident.
"I went to win a ball in the air and when I fell down I got hurt, but it is nothing serious," he said.