I am not a big fan of Jack Lemmon, but like some actors, Sean Connery is another, I think his career reached the pinnacle late in his career, which most actors are just coasting, finishing out the stretch. Lemmon doesn't do much for me in films from the 50s and 60s, but he is sublime in GGGR. I wouldn't say he out-acts anyone in that film, but he plays Levine brilliantly.