Chelsea have agreed a club-record fee of £26m with Lyon for Ghanaian midfielder Michael Essien.
The 22-year-old, who has been at the centre of a tug of war between the two clubs all summer, has agreed a five-year contract with Chelsea and will undergo a medical on Tuesday.
Lyon president Jean-Michel Aulas said: “It is with great regret that Michael will leave Lyon. We wanted to keep him but we cannot make him stay.
“It is a wrench but for the club this is a good deal.
“We have talked about Michael’s situation in great detail and we have decided it is better if we let him go.”
The fee for the 22-year-old is a record in transfers involving Ligue 1 players.
Ivory Coast striker Didier Drogba set the previous record when he left Marseille for Chelsea for an estimated €37.5m in July last year.
Chelsea, club official Bernard Lacombe said, would pay cash next week.
“Financially, it’s an extraordinary operation,” he said.
“It’s one third of our budget and it represents the entire budget of some Ligue 1 clubs.”
Essien’s arrival at Stamford Bridge ends the summer’s longest-running transfer saga.
Chelsea have seen bids of £10m, £16.75m, £18m, £21m and £21m plus Tiago turned down by the French champions before finally reaching agreement.
Essien moved to France in 2000, joining Bastia from Ghana’s Liberty Professionals. He moved to Lyon in 2003, for €7.8m, helping the club to successive league titles.
He was first linked with a move to Chelsea last spring, but Aulas was adamant that Essien would stay at the club.
After being left out of Lyon’s side for their opening three Ligue 1 games, coach Gerard Houllier denied reports that the player has gone on strike. However, the absence from the line-up encouraged Chelsea to make a fresh bid, with Chelsea owner Roman Abramovich and the club’s chief executive Peter Kenyon meeting Aulas for further talks which culminated in the £26m deal.