The 26-year-old former Leeds midfielder is seeking damages in London's High Court over comments made by the former England captain in his Sunday Telegraph column nearly 2 years ago.
Lineker's column said Kewell's transfer from Leeds to Liverpool made him "ashamed" of football, the court heard.
Both Kewell and Lineker were in court for the start of proceedings, which could last a week.
Kewell told the court the 2002/03 season at Leeds had "started off great", but then "players were getting sold right, left and centre".
He said he met agent Bernie Mandic's brother Nick in 2003 to discuss the possibility that he would be moving on.
"I needed to know what I was going to be doing for the next five years.
"We discussed clubs. There were a lot of clubs involved, but the main club was Liverpool because it was my dream move to go there. They were top of my list.
"I saw the article and I was shocked. I was amazed by what he said... I couldn't believe he wrote something like that."
Andrew Monson, counsel for Kewell, said his client had been libelled in three ways:-
1.That he had allowed his agent to approach Liverpool without the consent of Leeds and had therefore been disloyal and circumvented the rules which prohibited him from entering into negotiations with Liverpool.
2.That he had naively and stupidly allowed himself to be manipulated to his financial detriment
3.That he had discredited himself by willingly participating in a deeply dishonourable and financially dubious transfer.
Mr Monson said Kewell was seeking substantial damages against the defendants.
The Sunday Telegraph issued a statement in support of Lineker when Kewell announced his intention to sue last year.
It read: "We were surprised that Harry Kewell decided to issue a writ 10 months after the article was published.
"Mr Lineker is entitled to express his opinions, which are respected for their integrity throughout the world of soccer."