Chelsea have signed Wigan forward Victor Moses for an undisclosed fee thought to be around £9m.
The Champions League winners had four previous bids for the former England Under-21 international rejected.
A statement on Chelsea's official website read: "Chelsea Football Club is delighted to announce the signing of Victor Moses from Wigan Athletic."
No details were given on the contract for Moses, who played in the Blues' 2-0 victory at the DW Stadium on Sunday.
Chelsea are believed to have offered £7m up front, with a further £2m in add-ons.
Moses, 21, joined Wigan from Crystal Palace on a three-and-a-half-year deal in January 2010 for a reported fee of £2.5m.
He scored six goals for the Latics last season, playing a key part in their successful bid to stay in the Premier League.
Wigan manager Roberto Martinez was keen to keep the Nigeria international at the DW Stadium, but knew that Wigan were likely to accept a bid for the player if another club met their asking price.
Moses becomes Chelsea boss Roberto Di Matteo's second signing of the day, following the capture of Marseille full-back Cesar Azpilicueta.