Didier Drogba has revealed he did not want to move to Chelsea when the club first expressed an interest in him.
Drogba scored 29 goals last season
But the 26-year-old striker says their persistence eventually persuaded him to leave Marseille in a �24.5m deal.
"Financially and in a sporting sense I could not refuse Chelsea's offer - I hope I live up to their expectations," said the 26-year-old striker.
Drogba, of the Ivory Coast, will fly to London on Tuesday to sign a four-year contract with the Blues.
Drogba said the London club had fought off competition from several Serie A sides to secure his signature.
"I also had offers from Italian clubs, but going to Chelsea is an interesting challenge in my career and I'm glad to join them," he added.
"What convinced me to join Chelsea is that they really showed that they wanted me, and that counts a lot. I will give my best for them now.
"It's very hard to leave Marseille. I've had fantastic times there."
Marseille revealed that Chelsea offered double what Juventus were prepared to pay for Drogba.
And Marseille president Christophe Bouchet said the fee for the striker could be as much as �26.6m.
"What Chelsea offered was the double that of Juventus' offer," he said. "We could not let such an offer go.
"Everything was finalised this weekend. Didier has signed a four-year contract, and the estimated price tag is between 35 and 40m euros (�23.3m and �26.6m)."
Drogba will become Chelsea's record signing if he completes a move to the club, eclipsing the �17m paid for Damian Duff.
Drogba was footballer of the year in France last season.
He scored 29 goals last season, 11 of them in European competition, as Marseille reached the Uefa Cup final, losing 2-0 to Valencia.
The French side admitted last week that the striker, who joined from Guingamp for �4m in 2003, was set to join Chelsea.
Chelsea boss Jose Mourinho highlighted Drogba as his preferred replacement when Hernan Crespo sealed a season-long loan transfer to AC Milan.
Mourinho was keen to complete his squad for the new season before the Blues depart for a US tour on Wednesday, and is also set to sign Benfica midfielder Tiago.
Drogba will battle for a starting place with Kezman, Eidur Gudjohnsen and Adrian Mutu.
Petr Cech and Arjen Robben, who agreed transfers to Stamford Bridge back in January, are the other new arrivals alongside Drogba, Tiago, Kezman and Ferreira.
Marseille president Christophe Bouchet has promised to reinvest "65-80%" of the money received for Drogba on new players and salaries.
He has already identified Czech striker Jan Koller, Swede Zlatan Ibrahimovic and Cameroon's Samuel Eto'o as possible replacements.
Veteran France left-back Bixente Lizarazu is also poised to sign for the club from Bayern Munich.