to be performing at one’s best level
auf dem Höhepunkt seiner Leistung sein (auf dem hoehenpunkt seiner leistung sein)
"The athlete is at the top of his game this season."
"Der Athlet ist in dieser Saison in Bestform." (Der Athlet ist in dieser Saison in Bestform.)
to fail completely; to come to nothing
to be so surprised that you cannot speak
a little stupid or crazy
to believe that you are valuable and deserve respect
to be certain that something is true or will happen
being in a leading or important position in a field