Vitali Klitschko expects his brother Wladimir to beat Anthony Joshua because he knows he has "no second chance" in the twilight of his career.
Veteran Ukrainian Klitschko will step between the ropes at Wembley on Saturday to face IBF world heavyweight champion Joshua.
Former heavyweight champion Wladimir, 41, has not fought since he was sensationally beaten by Tyson Fury back in November 2015.
Vitali said his younger brother knows he may be entering the last chance saloon in London next week.
"Wladimir right now is focusing on the fight. He knows from this fight a lot depends on his future and his career," former heavyweight world champion Vitali told Sky Sports' 'Behind The Ropes'.
"It's the time to think about stopping and not fighting anymore, or continue his career."
He added: "Wladimir knows he has to dominate. Not to wait, to come in and show his performance.
"No other way. He knows that, I talked to him, many times. He knows that already well.
"Everything, his future depends on him, and that's why if Joshua loses the fight, he has a lot of space, because of his age. He has a next time to fight, to try to be the world champion.
"Wladimir doesn't have a second chance. That's why we expect full concentration from him and, of course, a good result."