Harrison (left) met Sosnowski at a news conference on Monday
Audley Harrison says he will target the Klitschko brothers if he manages to dethrone European heavyweight champion Albert Sosnowski in London on 9 April.
Harrison, 38, added that he is not interested in fighting WBA heavyweight champion and fellow Briton David Haye.
"No disrespect to David Haye, but no-one is talking about David Haye," said Harrison, an Olympic champion in 2000.
"They're all talking about the Klitschkos, so if I beat Albert, I want the Klitschkos."
Vitali Klitschko is the current WBC heavyweight champion, while his younger brother Wladimir owns the IBF and WBO belts. Either one is expected to fight Haye later this year if Haye defeats John Ruiz in April.
I want to get my London fans in their St George's T-shirts and I want to get nostalgic and hear chants of 'Audley', 'Audley', 'Audley'
However, Harrison, who won promoter Barry Hearn's Prizefighter tournament last October to keep his career afloat, admitted that defeat to his Polish opponent at Alexandra Palace would end his career.
He said: "All I'm interested in at the moment is Albert Sosnowski and he will not give up that belt easily. The worst thing I could do is look past Albert. If I can't get past him then there's nothing in the future."
Harrison won gold in the super-heavyweight division at the Sydney Olympics, but four defeats in eight fights left his career in the balance before Prizefighter offered him a route back.
But Harrison admits he nearly walked away from the sport and almost gave up on his oft-stated dream of winning a world title.
"I have a personal mission to be a world champion. Call me delusional or crazy but I call it reality," added Harrison.
"When my contract with the BBC ended [in 2003] I lost my feel for boxing and the passion for boxing died. I left England and almost didn't want to box as I was that disheartened - you saw that in my performances.
"I was a shell and I had no desire. I was a totally broken man and it took a long time to recover from that. It took a lot of soul-searching and I asked myself what I wanted to do and I said to myself I wanted to achieve my goals.
"I had to lick my wounds and go back to the drawing board. Ability gets you to the top but character keeps you there.
"I had certain characteristic flaws but it's been part of my learning and journey. I wasn't ready to be the next Lennox Lewis in 2004 and it was almost a blessing that I lost as I had a chance to grow through adversity.
"I've been through so much in my career but I'm still here, still believing, still persevering and that's what character is. My moment of destiny is really close but I have a real obstacle in front of me.
"If he beats me to a pulp then I will know it's over. If Albert Sosnowski beats Audley Harrison fair and square then there will be no excuses as I'm 100% physically, mentally and spiritually ready to win.
"I want to get my London fans in their St George's T-shirts and I want to get nostalgic and hear chants of 'Audley', 'Audley', 'Audley'.
"I want to hear the fans of boxing, the fans of Audley, the fans of perseverance and the fans of overcoming adversity and get back to boxing."
Sosnowski, who is based in Brentwood, Essex, but originally hails from Warsaw, claimed the title with an emphatic points victory over Italian Paolo Vidoz in December.
But the 30-year-old is best known for a shock stoppage win against Harrison's long-term rival and current British champion Danny Williams in 2008.