But the Bath captain is reluctant to draw comparisons between himself and the Leicester man.
"Johnno is a great player because he doesn't have bad games. I don't compare myself with him - it would probably depress me," he said.
"The only time I feel depressed or frustrated is when I am involved in the match 22 and I don't get on the field. Against Australia the boys played brilliantly, and I wasn't used. You don't feel part of it," he added.
Even with Johnson temporarily sidelined, Grewcock knew he could not take anything for granted in terms of selection.
"Second row is a very competitive position, and there are other guys around who are currently not in the England 22," said Grewcock. You cannot afford to have too many off-days. "